Publicaciones BCA

R Fernández-Gago, P Molist and F Rocha

Anatomical and histochemical features of the digestive system of Octopus vulgaris Cuvier, 1797 with a special focus on secretory cells.

Acta Zoologica, online, 2018.


This study reports a detailed anatomical and histological study of the digestive system of Octopus vulgaris. Emphasis was placed on characterising the glands and glandular cells and their distribution throughout the digestive tract. The use of classic histological and histochemical techniques revealed two morphological types of glandular cells: granular and mucous. Moreover, the histochemical analysis indicated specialisation of mucous glandular cells in the buccal mass, the submandibular gland and the caecum for secreting acid and neutral glycoconjugates. The cells of the anterior salivary glands are specialised for secreting neutral glycoproteins, and those of the posterior salivary glands are specialised for granular and mucous secretion. The oesophagus, crop and stomach lack glandular cells, but both granular and mucous glandular cells are found in the intestine. An unusual structure resembling the typhlosole of bivalves is described for the first time in the intestine of O. vulgaris. The highly ciliated epithelium and location of the structure in the anterior part of the intestine suggest a possible role in bypassing the caecum, stomach and intestine. We discuss how these cells and organs contribute to the process of digestion in the light of the present histological and histochemical data and of previously published information on the morphology and physiology of digestion in the octopus. © 2018 The Royal Swedish Academy of Sciences.

R Fernández-Gago, M Heß, H Gensler and F Rocha

3D reconstruction of the digestive system in Octopus vulgaris Cuvier, 1797 embryos and paralarvae during the first month of life.

Frontiers in Physiology, 8 (JUL), 2017.


Octopus vulgaris aquaculture is limited due to poor biological knowledge of the paralarval stages (e.g., digestive system functionality), their nutritional requirements (e.g., adequate live diet) and standardization of rearing techniques. These factors are important in explaining the high mortality rate observed in this developmental stage under culture conditions. For a better understanding of nutrition biology of this species, we investigated the 3D microanatomy of the digestive tract of the embryo and paralarvae during the first month of life. O. vulgaris paralarvae digestive system is similar to that in the adult. The «descending branch» has a dorsal position and is formed by the buccal mass, oesophagus and crop. Ventrally, the «ascending branch» is formed by the intestine and the anus. The digestive gland, the posterior salivary glands and the inner yolk sac (in the case of the embryo and hatched paralarvae) are located between the «ascending» and «descending» branches. In the curve of the U-shaped digestive tract, a caecum and the stomach can be found. The reconstructions reveal that anatomically the digestive system is already complete when the paralarvae hatch. The reconstruction of the buccal mass at different post-hatching days has demonstrated that all the necessary structures for food intake are present. However, the radula surface in contact with the pharynx is very small on the first day of life. Although the digestive system has all the structures to feed, the digestive gland and radula take longer to reach full functionality. We have established four development periods: embryonic, early post-hatching, late post-hatching and juvenile-adult. The differentiation between these periods was done by type of feeding (endogenous or exogenous), the state of maturation and hence functionality of the digestive gland, type of growth (linear, no net, or exponential), and measurement of the arm lengths with respect to the mantle length. 3D reconstruction represents a new tool to study the morphology and functionality of the cephalopod digestive system during the first days of life. © 2017 Fernández-Gago, Heß, Gensler and Rocha.

A Escánez, Á Guerra, F Rocha and F Lozano-Soldevilla

New records of the scaled squid, lepidoteuthis grimaldii joubin, 1895 in the canary islands, eastern atlantic ocean (Cephalopoda, oegopsida, lepidoteuthidae).

Spixiana, 40 (1): 7-12, 2017.


Two well conserved female specimens of the uncommon soft-scaled squid Lepidoteuthis grimaldii Joubin, 1895 (Lepidoteuthidae, Oegopsida) were caught in Canary Island waters: a maturing female of 580 mm dorsal mantle length found dead on the surface at 27°38′ N, 18°01′ W (near El Hierro Island); an immature female of 350 mm dorsal mantle length captured by commercial open midwater trawl at 28°48′ N, 16°00′ W (north of Tenerife Island), between 342 and 487 m depth. This is the first report of an adult of this species from the Canary Islands. Morphological data are presented and the bathymetric distribution of this species in Canary waters is discussed. © 2017, Verlag dr Friedrich Pfeil. All rights reserved.

A Ramos, J L Sanz, J L Pelegrí, L Fernández-Peralta, P J Pascual-Alayón, F Ramil, S Castillo, E García-Isarch, F Rocha, M Gil and B Calero

An Overview on Biodiversity and Ecosystems Off Mauritanian Deep-Waters.

In Deep-Sea Ecosystems Off Mauritania: Research of Marine Biodiversity and Habitats in the Northwest African Margin, 615-660, 2017.


Human activities in continental margins have progressively increased during the last decades, threatening vulnerable marine ecosystems in many continental slopes, such as cold-water coral reefs, seamounts and canyons. In order to protect these ecosystems and ensure the sustainable management of resources, countries and organizations should endorse effective policy actions. However, nowadays about only 0.8% of the oceans and 6% of the territorial seas belong to conservation area systems, a lack of protection that is particularly acute in deep-sea waters. The Mauritanian continental margin is the outcome of exceptional marine features, with abrupt canyon systems, sediment slides and a giant carbonate. © Springer Science+Business Media B.V. 2017.

F Rocha, R Fernández-Gago, F Ramil and A Ramos

Cephalopods in Mauritanian waters.

In Deep-Sea Ecosystems Off Mauritania: Research of Marine Biodiversity and Habitats in the Northwest African Margin, 393-417, 2017.


A total of 16,036 cephalopods belonging to 48 species were caught on the Mauritanian continental shelf and slope, between 80 and 2000 m depth, in November-December of 2007-2010 during the joint Spanish-Mauritanian surveys. Samples were collected using a commercial bottom trawl. Ommastrephidae was the most abundant family (71.1%) in number and weight. Neritic and benthic species of Loliginidae, Octopodidae and Sepiidae represented 7.3, 6.2 and 5.3% of the total number, respectively. A checklist of 132 Mauritanian species is shown. The geographical and bathymetric distribution of species sampled in the area is discussed. Eight species, Mastigoteuthis flammea, Cycloteuthis akimushkini, Muusoctopus fuscus, M. janarii, Bathypolypus arcticus, B. biardii, B. valdiviae and Graneledone verrucosa are recorded for the first time in Mauritanian waters. This is the first time that M. fuscus is cited in Atlantic waters and that B. valdiviae is observed in the northern hemisphere. Two main cephalopods assemblages, Shelf and Slope, were identified in the zone. Both are largely dominated by ommastrephid species which could constitute an important resource not currently exploited in the area. This work provides the first data on benthic octopods species that inhabit the deep waters of Northwest Africa. © Springer Science+Business Media B.V. 2017.

J M Smith, G J Pierce, A F Zuur, H Martins, M C Martins, F Porteiro and F Rocha

Patterns of investment in reproductive and somatic tissues in the loliginid squid Loligo forbesii and Loligo vulgaris in Iberian and Azorean waters.

Hydrobiologia, 670 (1): 201-221, 2011.


The veined squid, Loligo forbesii, is found throughout the northeast Atlantic, including the waters off the Iberian Peninsula, and is a socio-economically important cephalopod species, sustaining several small-scale commercial and local artisanal fisheries. This study uses Iberian and Azorean trawl survey and fishery landings data from 1990 to 1992 and employs additive modelling to examine the relationships amongst somatic growth, season and gonad growth, in an attempt to determine the relative importance of intrinsic (e. g. nutritional state and body size) and extrinsic (temperature and daylight) factors which contribute to maturation in L. forbesii. We compare the results with those from a comparative analysis of contemporaneous data on Loligo vulgaris from the Iberian coast, and with a re-analysis of previously published results for L. forbesii in Scottish waters. Reproductive organ weight in both sexes of L. forbesii from all ports shows seasonal patterns with a fall/winter peak in maturation, as is expected with the animals’ year-long life cycle. Two maturity peaks (spring and winter) were found for both Azores L. forbesii males and females, possibly evidence of two breeding cohorts, with males maturing approximately 1 month earlier than females in both seasons. For L. vulgaris, three annual peaks in reproductive weight were identified. With the exception of L. forbesii males from Scottish waters, in all study animals, the partial effect of mantle length and mantle weight on reproductive weight is positive up to large body sizes. The relationship between nutritional status and reproductive weight is also generally positive. Geographic variation in the relationships, as seen between Scottish males and samples from the other study areas, is hypothesised to be largely attributable to local differences in environmental conditions (productivity, food availability, temperature, upwelling), although differences between L. forbesii from the Azores, Scotland and mainland Europe may also relate to previously documented genetic differences. © 2011 Springer Science+Business Media B.V.

C Hermosilla, F Rocha and V D Valavanis

Assessing Octopus vulgaris distribution using presence-only model methods.

Hydrobiologia, 670 (1): 35-47, 2011.


The distribution of the common octopus (Octopus vulgaris) in the Mediterranean and Eastern Atlantic waters is evaluated using two presence-only analyses: The maximum entropy model (Maxent) and the ecological niche factor analysis (ENFA). Maxent predicts those geographical areas that satisfy the environmental or abiotic requirements of a species while ENFA explores the niche and habitat preferences of O. vulgaris. The analyses were implemented recovering the spatial information from 213 octopus presence data collected from surveys and bibliographical records. Together, these analyses provided reasonable estimates of the species distribution and the octopus habitat. Among the gathered set of explanatory environmental variables, sea bottom temperature, sea bottom salinity, surface dissolved oxygen and sea surface chlorophyll-α appear as the main variables involved in O. vulgaris distribution. These results were confronted with the available literature. © 2011 Springer Science+Business Media B.V.

J L P Muñoz, M A L Patiño, C Hermosilla, M Conde-Sieira, J L Soengas, F Rocha and J M Míguez

Melatonin in octopus (Octopus vulgaris): Tissue distribution, daily changes and relation with serotonin and its acid metabolite.

Journal of Comparative Physiology A: Neuroethology, Sensory, Neural, and Behavioral Physiology, 197 (8): 789-797, 2011.


Information regarding melatonin production in molluscs is very limited. In this study the presence and daily fluctuations of melatonin levels were investigated in hemolymph, retina and nervous system-related structures in the cephalopod Octopus vulgaris. Adult animals were maintained in captivity under natural photoperiod and killed at different times in a regular daily cycle. Levels of melatonin, serotonin (5-HT) and its acid metabolite (5-hydroxyindole acetic acid, 5-HIAA) in the hemolymph, retina, optic lobe, and cerebral ganglion were assayed by HPLC. Melatonin content fluctuated rhythmically in the retina and hemolymph, peaking at night. In the retina, but not in the other neural tissues, the rhythm was opposite to that of 5-HT, which displayed basal levels at night. Also, 5-HIAA levels in the retina were higher during the night, supporting that rhythmic melatonin production could be linked to diurnal changes in 5-HT degradation. The high levels of melatonin found in the retina point to it as the major source of melatonin in octopus; in addition, a large variation of melatonin content was found in the optic lobe with maximal values at night. All these data suggest that melatonin might play a role in the transduction of the light-dark cycle information for adjustment of rhythmic physiological events in cephalopods. © 2011 Springer-Verlag.

E Canali, G Ponte, P Belcari, F Rocha and G Fiorito

Evaluating age in Octopus vulgaris: Estimation, validation and seasonal differences.

Marine Ecology Progress Series, 441: 141-149, 2011.


Several internal structures have been used to estimate age in the cephalopod Octopus vulgaris, but with limited accuracy. We estimated age by investigating growth increments (rings) in the upper beaks of octopus collected between 2003 and 2010 in the Bay of Naples, Italy (Mediterranean Sea). To validate the daily periodicity of ring deposition, ‘thermal shock marking’ was for the first time applied to live octopuses fished between 2009 and 2010; this method produced a mark on the beak corresponding to the day of thermal shock, enabling us to elucidate the relationship between ring number and time elapsed (i.e. ∼30 d). In addition, rings were counted in >700 preserved specimens of O. vulgaris collected between 2003 and 2009, also in the Bay of Naples. The estimated age of of these octopuses ranged from about 70 to 370 d. Specimens with similar body weights had different numbers of rings, confirming the view that body size is a not a good index of age. Additionally, the relationship between body weight and number of rings was affected by sex and season, with the distance between rings clearly correlated to seasonal temperature oscillations. Our data suggest that different cohorts of octopus exist in the Bay of Naples and that temperature has a strong influence on growth. Overall the results demonstrate that growth increments in the upper beak of O. vulgaris provide a reliable method of aging that can be applied to assessing differences in the growth patterns in wild populations, and one that provides a record of environmental influences upon an individual. © Inter-Research 2011.

C A Hermosilla, F Rocha, G Fiorito, Á F González and Á Guerra

Age validation in common octopus Octopus vulgaris using stylet increment analysis.

ICES Journal of Marine Science, 67 (7): 1458-1463, 2010.


Daily periodicity of growth increments in stylets was validated in wild-caught Octopus vulgaris maintained under controlled conditions. It was corroborated by staining the stylets either with oxytetracycline (OTC) or tetracycline (TC), and comparing the number of rings produced with the number of days elapsed. In all, 19 animals (10 males and 9 females; 680-1470 g body weight, BW) were injected with OTC in Vigo (mean 124 mg kg-1), and another six animals (1 male and 5 females; 248-570 g BW) with TC at Naples (mean 120 mg kg-1). The animals were successfully maintained in captivity until sacrificed for up to 6 (one animal), 9 (one animal), 18 (the six animals from Naples), and 21 (17 animals) days. The number of increments counted in transverse stylet sections was 18.9 ± 1.4 and 20.5 ± 1.5 for octopuses maintained for 18 and 21 d, respectively. The mean rate of increment formation was 1.02 increments per day, suggesting a periodicity of 1 increment per day in the stylet. Consequently, the results successfully validate daily increment deposition in O. vulgaris stylets in the size range analysed. © 2010 International Council for the Exploration of the Sea. Published by Oxford Journals. All rights reserved.

C M Ibáñez, P A Camus and F J Rocha

Diversity and distribution of cephalopod species off the coast of Chile.

Marine Biology Research, 5 (4): 374-384, 2009.


Cephalopods are increasingly acknowledged as an ecologically important group in Chilean ecosystems, but are also one of their less-known biogeographic components. Notably, this group is represented virtually exclusively by non-endemic species, although we hypothesized that their distribution over the coast should be constrained by similar physical determinants to those affecting endemic taxa. We thus present a first evaluation of the latitudinal patterns of diversity and distribution of cephalopod species in Chile, based on geographical data obtained from a review of the available literature. We constructed presence-absence binary matrices of coastal and oceanic species in 20 latitudinal units (2°), for then calculating the respective similarity matrices to obtain a distribution dendrogram using hierarchical cluster analysis (UPGM). The original binary matrices were resampled performing 1000 stochastic reassignments to calculating the 95th percentile as the criterion to identify significant clusters. Statistical comparisons between distributional groupings were performed using ANOSIM. We recorded 86 cephalopods in Chile, including oceanic (71) and coastal (15) species. Species richness showed two major breaks at 30° S and 42° S, and decreased toward higher latitudes. Cephalopod species showed well-defined endpoints of distribution within the Chilean coast, differentiating three main biogeographical units: northern (18-30° S), central (30-42° S) and southern (42-56° S) areas. Biogeographical patterns of cephalopod species in Chile showed no particular difference with those already described for most Chilean taxa. The marked distribution breaks of cephalopods at 30° and 42° S suggest that external forcing and physical factors other than temperature gradients may strongly constrain their dispersal.

P Bustamante, A F González, F Rocha, P Miramand and A Guerra

Metal and metalloid concentrations in the giant squid Architeuthis dux from Iberian waters.

Marine Environmental Research, 66 (2): 278-287, 2008.


This study investigated 14 trace elements (Ag, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, V and Zn) in the tissues of the giant squid Architeuthis dux from the Mediterranean and Atlantic Spanish waters. As for other families of cephalopods, the digestive gland and the branchial hearts of Architeuthis showed the highest concentrations of Ag, Cd, Co, Cu, Fe, Ni, Se, V and Zn, highlighting their major role in the bioaccumulation and detoxification processes. With the exception of Hg, the muscles showed relatively low trace element concentrations. Nevertheless, this tissue contained the main proportion of the total As, Cr, Hg, Mn, Ni, and Zn body burden because muscles represent the main proportion of the squid mass. These findings suggest that the metal metabolism is overall the same as other cephalopod families from neritic waters. In females, Zn concentrations increased in the digestive gland with the squid’s weight likely reflecting physiological changes during sexual maturation. Comparing the trace element concentrations in the tissues of Architeuthis, higher Ag, Cu, Hg and Zn concentrations in the squid from the Mediterranean reflected different exposure conditions. In comparison to other meso-pelagic squids from the Bay of Biscay, Cd concentrations recorded in the digestive gland suggest that Architeuthis might feed on more contaminated prey or that it displays a longer life span that other cephalopods. © 2008 Elsevier Ltd. All rights reserved.

M E Garci, J E Trigo, S Pascual, A F González, F Rocha and A Guerra

Xenostrobus securis (Lamarck, 1819) (Mollusca: Bivalvia): First report of an introduced species in Galician waters.

Aquaculture International, 15 (1): 19-24, 2007.


The presence of the non-indigenous species, the black-pygmy mussel Xenostrobus securis, is reported here for the first time in an intense shellfish farming area off Galicia (NW Spain). Very high concentrations of this mytilid bivalve have colonized estuarine waters located at the inner part of the Ria de Vigo. The invasive role of X. securis is discussed in the context of the wide ecological tolerance of the species and the recent finding of settlements of this species on numerous colonies of the economically-important blue mussel Mytilus galloprovincialis. The mode of introduction of the black-pygmy mussel is also discussed in relation to human management activities. © Springer Science+Business Media, Inc. 2006.

F Rocha, J Otero, R Outeiral, Á F González, J Gracia and Á Guerra

Modelling small-scale coastal fisheries of Galicia (NW Spain) based on data obtained from fisheries: The case of Sepia officinalis.

Scientia Marina, 70 (4): 593-601, 2006.


The small-scale cuttlefish (Sepia officinalis) fishery in Galician waters (NW Spain) was studied using a model based on data obtained from fishers. This model was applied using information obtained from the small-scale Galician fleet in 1998. A total of 139 personal interviews were carried out at 62 Galician ports. This information was used to estimate catches per unit effort (CPUE) and total catch for the cuttlefish gillnet fishery. The fleet, which fishes in Galician waters within ICES divisions VIIIc and IXa, was composed of two groups: 600 vessels fishing for cuttlefish in only five months of the year (short season: November to March), and 141 vessels fishing for cuttlefish all year (extended season). Estimated total catch during the fishing season for the whole Galician fleet was 1301 t (869 t short season and 432 t extended season) and average CPUE values were 14.5 kg haul-1 trip-1 vessel-1 (short season) and 12.8 kg haul-1 trip-1 vesse-1 (extended season). To test the reliability of the model, the outputs obtained from the model for a subset of 37 ports (59.7% of all ports) were compared with the official catch statistics for these ports. Differences between total catches estimated by the model and those determined directly at these ports were not significant.

A Chapela, Á F González, E G Dawe, F J Rocha and Á Guerra

Growth of common octopus (Octopus vulgaris) in cages suspended from rafts.

Scientia Marina, 70 (1): 121-129, 2006.


Two ongrowing experiments were conducted using a raft deployed for rearing mussels during summer and winter in the Ria of Vigo, Galicia, NW Spain. Two 3 m × 1.5 m × 6 m galvanized iron ongrowing cages were suspended from this platform, each equipped with dens constructed from PVC pipe. Small common octopus (Octopus vulgaris) were captured by the small-scale creel fishery in the ria and placed in one of two sex-specific experimental cages. Specimens were fed a standard diet (fish, decapod crustacean and mussels) at a daily feeding rate of 5% of the total weight of the animals in each cage. Due to the very high mortality as a result of decreased salinity in the winter experiment and spawning during the summer experiment, only data from the first 75 days of each experiment were compared. Growth rates were significantly higher in summer than in winter for both sexes, which was probably due to higher ambient culture temperatures during summer. Mortality was also higher during summer than winter. It was concluded that culture of common octopus on mussel rafts may be viable, especially if problems related to salinity, the acquisition of specimens from the wild and losses due to spawning can be reduced.

Ma.P. Sieiro, S P Aubourg and F Rocha

Seasonal study of the lipid composition in different tissues of the common octopus (Octopus vulgaris).

European Journal of Lipid Science and Technology, 108 (6): 479-487, 2006.


Seasonal variation of octopus (Octopus vulgaris) lipid composition was investigated in four tissues: arm, mantle, ovary and digestive gland. A non-homogeneous fat distribution was observed, with the digestive gland exhibiting a higher (p <0.05) lipid content than the other tissues. The ovary showed a higher (p <0.05) fat content than both muscle tissues, reaching its highest (p <0.05) value in winter. Neutral lipids – free fatty acids (FFA), triacylglycerols, and sterols (ST) – exhibited their highest (p <0.05) concentrations in the digestive gland and their lowest (p <0.05) values in muscle tissues. The phospholipid (PL) content of the ovary was the highest (p <0.05) of all tissues analysed, with the PL content also being significantly (p <0.05) higher in the digestive gland than in arm and mantle. The concentrations of most lipid classes (FFA, PL and ST) exhibited a seasonal variation. The fatty acid composition showed a remarkable difference between the digestive gland and all other tissues analysed. Thus, the digestive gland exhibited higher (p <0.05) contents in monounsaturated fatty acids and also lower (p <0.05) contents in both saturated (SFA) and polyunsaturated (PUFA) fatty acids. The highest mean values in SFA and PUFA were observed in ovary and muscle tissues, respectively. A seasonal effect was observed for SFA and PUFA. © 2006 WILEY-VCH Verlag GmbH & Co. KGaA.

S Pascual, F Rocha and A Guerra

Gross lesions in the Hubb octopus Octopus hubbsorum.

Marine Biology Research, 2 (6): 420-423, 2006.


A visible pathological condition located in the arms and mantle of the Hubb octopus Octopus hubbsorum from the Northeast Pacific waters is described for the first time. Histological sections confirmed later stages (fibrosis) of a chronic inflammatory condition of unknown aetiology. © 2006 Taylor & Francis.

J Otero, F Rocha, A F González, J Gracia and A Guerra

Modelling artisanal coastal fisheries of Galicia (NW Spain) based on data obtained from fishers: The case of Octopus vulgaris.

Scientia Marina, 69 (4): 577-585, 2005.


The small-scale common octopus (Octopus vulgaris) fishery in Galician waters (NW Spain) was studied using a model based on information obtained from fishers. The Gómez-Muñoz model was applied using information obtained from the artisanal Galician fleet from 1998 to 2000. This information was used to estimate catches per unit of effort (CPUE) and total catch for the whole directed creel fishery. A total of 73 interviews were conducted in 22 ports in the west part of ICES division VIIIc and 75 interviews in 16 ports in the north part of ICES division IXa. The estimated total catch during the fishing season for the whole Galician fleet was 5214 t (2528 t in VIIIc and 2686 t in IXa), and the average CPUE for the VIIIc and IXa fishing grounds obtained from the model was 44.11 and 23.83 kg haul-1 respectively. To test the reliability of the model, the outputs obtained for a subset of 35 ports (19 in VIIIc and 16 in IXa), were compared with the official statistics of these ports. The average official catch from 1997 to 2000 and estimated total catch data were significantly correlated.

A F González, J Otero, A Guerra, R Prego, F J Rocha and A W Dale

Distribution of common octopus and common squid paralarvae in a wind-driven upwelling area (Ria of Vigo, northwestern Spain).

Journal of Plankton Research, 27 (3): 271-277, 2005.


The variation of paralarval abundance in a region subjected to wind-driven upwelling (Ria of Vigo, northwestern Spain) was studied. Research cruises were undertaken during the favourable upwelling season (May to October) in 2000 and 2001. Each cruise included biological and hydrographic sampling and consisted of five stations in waters located to the east and west of the Cies Islands. A total of 221 paralarvae of Octopodidae and Loliginidae were collected over the 12-month study period. During 2000, higher abundance of paralarvae was observed in July, September and October for Loligo vulgaris and Octopus vulgaris. In 2001, abundance of both species was higher in May and also in September for O. vulgaris. The mantle length of the paralarvae varied from 1.25 to 2.25 mm and from 1.00 to 4.90 mm within the O. vulgaris and L. vulgaris individuals, respectively. The presence/absence of upwelling modulates the abundance and spatial distribution of loliginid and octopod paralarvae. The relationship between the distribution and movement of these paralarvae in the Ria of Vigo seems to follow the circulation system defined for this area; when the upwelling extends its influence inside the Ria, the paralarvae are transported to the inner part in a west-east direction.

F Rocha, J Gracia, Á F González, C M Jardón and Á Guerra

Reliability of a model based on a short fishery statistics survey: Application to the Northeast Atlantic monkfish fishery.

ICES Journal of Marine Science, 61 (1): 25-34, 2004.


A model based on a short fishery statistics survey was applied to estimate catch and catch per unit effort (cpue) of the Galician monkfish (Lophius spp.) trawl fleet during 1998. In all, 35 interviews were conducted with fisheries personnel in ICES Divisions IXa, VIIIc, VIIId, and VIIIe (coastal offshore fishing grounds) and 44 in VIIb, VIIc, VIIj, and VIIk (Grand Sole fishing ground). Reliability of the model estimates was tested using: (i) registered fish market landings at 38 ports; (ii) landings data from sale invoices at six of these ports (93.8% of total landings of the species); (iii) 29 observers’ trips made on board coastal offshore trawlers and the logbook of one Grand Sole trawler. Estimated mean total catch from the model was 5110 t (602 t coastal offshore, 4508 t in Grand Sole) and cpue values were 36.2 kg haul-1 vessel-1 coastal offshore and 104.4 kg haul-1 vessel -1 Grand Sole. Differences between the values of cpue estimated by the model and those determined directly in both fisheries were not significant However, there were differences between the total catch estimated by the model and the total landings deduced from sale invoices and Galician fish market information. © 2003 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.

A Guerra, A F González, E G Dawe and F Rocha

Records of giant squid in the north-eastern Atlantic, and two records of male Architeuthis sp. off the Iberian Peninsula.

Journal of the Marine Biological Association of the United Kingdom, 84 (2): 427-431, 2004.


A review of the verified reports to date of Architeuthis spp. showed that 33.9% (115 specimens) of worldwide reports were derived from the north-eastern Atlantic. The sex of each specimen, nature of the report, as well as the season and area of collection are presented. Biological data are presented on the two first males of Architeuthis sp. captured off the Iberian Peninsula. The first male (42 kg and 98cm mantle length) was caught at 43°54.26′N 5°29.38′W by pair trawlers on 13 September 2002. Spermatophores ranged from 11 to 20cm in length. The peculiar observation of other spermatophores embedded in the skin near the proximal part of the ventral, ventro-lateral and dorso-lateral arms is discussed. The second male (66 kg and 122 cm mantle length) was found floating on the surface off Gijón on 16 September 2003. Although mature, no spermatophores embedded in the skin were observed. A comparison was undertaken of several morphometric measurements between these two males and five other north-eastern Atlantic males from which data were available.

F Rocha and M A Vega

Overview of cephalopod fisheries in Chilean waters.

Fisheries Research, 60 (1): 151-159, 2003.


This paper describes the history of cephalopod fisheries in Chile over the past 40 years. Continuous monitoring of three species was undertaken between 1978 and 1999: Loligo gahi, Dosidicus gigas and Octopus mimus. Total cephalopod catches increased from 69 tonnes in 1978 (0.13% total mollusc catch) to 3503 tonnes in 1996 (3.64%). A maximum haul of 15,169 tonnes was taken in 1992 (11.27% total mollusc catch). Small-scale fisheries accounted for the majority of cephalopod captures and industrial catches were rare. L. gahi is caught year-round mainly in the south of Chile, with maximum catches in summer and autumn. Catches of D. gigas are also year-round, mainly concentrated in central Chile. O. mimus has been fished since 1978, although recorded as Octopus vulgaris until the 1990s. The O. mimus fishery is located on the north coast of Chile, and catches are made for the most of the year. Octopus has been landed in the south of Chile since 1991, and is considered as O. mimus in capture statistics despite the fact that several species are represented, including Enteroctopus megalocyathus. © 2002 Elsevier Science B.V. All rights reserved.

R Villanueva, A Arkhipkin, P Jereb, E Lefkaditou, M R Lipinski, C Perales-Raya, J Riba and F Rocha

Embryonic life of the loliginid squid Loligo vulgaris: Comparison between statoliths of Atlantic and Mediterranean populations.

Marine Ecology Progress Series, 253: 197-208, 2003.


Egg masses of the loliginid squid Loligo vulgaris Lamarck, 1798 are attached to hard substratum or branched sessile organisms on the sea bottom. Embryonic development lasts from a few weeks to a few months, depending on the environmental water temperature. Because embryonic statolith growth of L. vulgaris is very sensitive to temperature under laboratory conditions, we analyzed the possibilities of determining past events in the squid’s early life from analysis of the embryonic area of statoliths of wild squid populations. The relationship between egg-incubation temperature and daily growth of embryonic statoliths under laboratory conditions was determined by tetracycline markings at 10 incubation temperatures ranging from 12 to 24.7°C. In addition, the mean width of embryonic increments in statolith collections of wild L. vulgaris from the Eastern Atlantic (Saharan Bank and NW Iberian Peninsula) and the Mediterranean Sea (Central and Eastern) was calculated. The temperature inferred from the embryonic increment widths of the statoliths of wild squid indicates that embryonic development of L. vulgaris in the regions sampled is likely to occur at temperatures ranging from 12 to 17°C. Mediterranean squid have wider embryonic increments than Atlantic squid, reflecting the slightly higher water temperatures in the Mediterranean Sea during the development of the egg masses. Eggs of L. vulgaris spawned off the NW Iberian Peninsula were estimated, on average, to remain at sea for 47 d, 1 wk longer than Mediterranean eggs (nearly 1 mo longer when comparing minimum and maximum ranges). A longer incubation time for egg masses attached to the sea bottom increases mortality risks. Conversely, slow development at a lower temperature can improve yolk conversion, producing larger hatchlings, and increased hatching competence is expected from such squid. Therefore, a compromise between longer-versus-shorter incubation time and related characteristics does exist.

A F González, A Guerra and F Rocha

New data on the life history and ecology of the deep-sea hooked squid Taningia danae.

Sarsia, 88 (4): 297-301, 2003.


Three specimens of Taningia danae were captured in the northern Spanish (eastern Atlantic) waters in late 2000. The total weights of the animals, two females and one male, were 66, 124 and 19 kg, respectively. Both females were maturing with no trace of eggs in the oviduct. The potential fecundity of the largest female was close to 5 million oval-shaped oocytes ranging from 0.4 to 1 mm. This female represented the heaviest record of T. danae to date. A description of the first mature male of this species is also undertaken. The reproductive strategy adopted by this species seems to rely on multiple spawning. The most remarkable feature of the male was the presence of a long penis with a total length of 73 cm that protruded 23 cm beyond the mantle. The number of growth increments in the statoliths was 647 and 1052, for each female, respectively. Assuming that these growth increments are deposited daily, the estimated age of these specimens would be 21 and 33 months, respectively. Remains of the blue whiting Micromesistius poutassou, some exoskeleton fragments of crustaceans and small hooks of Gonatus sp. were present in their stomach contents. The geographical and vertical distribution and the possible influence of water temperature and upwelling events on the growth of this species are discussed.

S Pascual, M A Vega, F J Rocha and A Guerra

First report of an endoparasitic epicaridean isopod infecting cephalopods.

Journal of Wildlife Diseases, 38 (2): 473-477, 2002.


This is the first report of an epicaridean isopod infecting cephalopods. Three cryptoniscus larvae (Isopoda, Epicaridea) were recognized externally and found entirely embedded in the oral bulb at the beginning of the esophagus of two female Patagonian squid (Loligo gahi) sampled in North Peruvian and South Chilean waters, respectively. There was an extremely low prevalence (<2%) and mean intensity (one) of infection which we believe indicated an accidental infection. However, the tissue location indicated successful penetration and colonization of the squid host.

A F González, A Guerra, F Rocha and P Briand

Morphological variation in males of Vulcanoctopus hydrothermalis (Mollusca, Cephalopoda).

Bulletin of Marine Science, 71 (1): 289-298, 2002.


Seventeen new specimens of Vulcanoctopus hydrothermalis were collected during the French cruise HOPE 99 between 1-21 May 1999. The animals were caught at 2631 m depth at 12°48.7′N, 103°56.43′W. Vacuums and creels in seven different submersible samplings collected the specimens. Animals ranged from 22 to 56 mm dorsal mantle length (ML). A total of 26 morphometric and 10 meristic characters were measured and counted. Indices were calculated. Arms with suckers in two rows. Each row with the same number of suckers. The sucker addition is faster in small animals than in bigger animals with a near to total cessation of addition of new suckers during the later stages of arm growth. Arm formula typically or Mean and range of variation of morphological characters examined are given and discussed. The absence of females suggests the existence of spatial segregation by sex. Male maturation is also discussed.

A Guerra, A F González, F J Rocha, R Sagarminaga and A Cañadas

Planktonic egg masses of the diamond-shaped squid Thysanoteuthis rhombus in the eastern Atlantic and the Mediterranean Sea.

Journal of Plankton Research, 24 (4): 333-338, 2002.


Eight planktonic egg masses of the diamond-shaped Thysanoteuthis rhombus observed from 1995 to 2000 are described. Four were found in the western Mediterranean and the others were found off the Canary Islands. The egg masses from the Canary Islands are the first records for the eastern Atlantic. All were found near the surface at the end of summer and the beginning of autumn. The planktonic egg masses were dense, resilient oblong cylinders with rounded tips ranging from 80 to 130 cm in length and between 15 and 20 cm in diameter. Egg capsule dimensions ranged from 2.8 to 3.4 mm and total length of the newly hatched paralarvae was between 2.5 and 2.8 mm. Each egg mass contained an estimated 24 100-43 800 eggs. Some new characters that should help identification of the paralarvae, such as arm formulae, presence of an incipient keel-shaped membrane on some arms, and the type and chromatophore pattern are given. Ecological factors influencing the presence and distribution of these egg masses are discussed.

A Guerra, A F González, F Rocha, M Segonzac and J Gracia

Observations from submersibles of rare long-arm bathypelagic squids.

Sarsia, 87 (2): 189-192, 2002.


Two rare and unique cephalopods were observed and filmed at 2950-3010 m depth off the coasts of Ghana and Ivory Coast in July 1992, a third at 4735 m north of Brazil in September 1988 and a fourth specimen northwest of Mauritius in the Indian Ocean in May 2000 at 2576 m. The first of these specimens was filmed 20 cm above a sedimentary seafloor. The second observation was filmed in mid-water 40 min later and during the same dive. The cephalopods belonged to an unknown species. The most remarkable features are the extremely long filaments at the tip of each arm and tentacle, and their extraordinarily wide rhomboid fins, occupying about two-thirds of the mantle length. The morphology and behaviour of these unknown cephalopods are described from video records obtained from the manned submersible Nautile. Possible systematic placement of these specimens is discussed.

M A Vega, F J Rocha, A Guerra and C Osorio

Morphological differences between the Patagonian squid Loligo gahi populations from the Pacific and Atlantic Oceans.

Bulletin of Marine Science, 71 (2): 903-913, 2002.


A total of 243 specimens of the loliginid squid Loligo gahi was examined. The samples comprised 82 specimens (34 males and 48 females) from Peruvian waters and 94 (78 males and 16 females) from Southern Chilean waters in the Pacific Ocean, and 58 (35 males and 23 females) from waters around the Falkland Islands in the Atlantic Ocean. Size of the specimens ranged from 83 to 201 mm dorsal mantle length (ML). After defrosting at room temperature, sex, maturity stage, 23 morphometric and five meristic characters from each individual were recorded. Measurements and counts were obtained by the same sampler and under similar conditions. In order to test potential differences between these three populations a Discriminant Analysis was undertaken using morphometric characters. Meristic characters were analyzed using the U Mann-Whitney non-parametric test. Males and females from Falkland Islands population differed in all morphometric characters examined showing higher sexual dimorphism than those from Peruvian and Southern Chilean waters. Significant differences between sexes also occurred in Peruvian population attached to gladius width, gladius rachis length and lower hood length. However, no significant differences between sexes were found in the Chilean population. Significant differences between the three populations, comparing males and females separately, were found. All morphometric characters, except fin length and gladius width, and the number of teeth in the largest sucker of the third arm and the number of gill lamellae accounted for these differences. Hard structures (gladius, beaks and statoliths) proved to be more accurate than soft body parts to separate between populations. Systematics and evolutive implications of the differences found are discussed.

A F González, A Guerra, F Rocha and J Gracia

Recent findings of the giant squid Architeuthis in northern Spanish waters.

Journal of the Marine Biological Association of the United Kingdom, 82 (5): 859-861, 2002.


There are just a few records of giant squid of the species Architeuthis captured alive. Two living sub-adult females of Architeuthis of 180 and 135 cm mantle length with total weights of 148 and 81 kg respectively, were caught 34 miles offshore in northern Spanish Atlantic waters (43°52.54′N-05°18.74′W) in December 1999 and January 2001. From April 1999 to January 2000 in the same area, another giant squid of 102 kg as well as a single tentacle measuring 5 m, and another tentacle of 2 m long were caught. Another five living specimens were captured and 11 more animals were caught dead during the last 15 years in the same area.

A Guerra, A F González and F Rocha

Appearance of the common paper nautilus Argonauta argo related to the increase of the sea surface temperature in the north-eastern Atlantic.

Journal of the Marine Biological Association of the United Kingdom, 82 (5): 855-858, 2002.


The relationship between the increase of the sea surface temperature observed off the Galician coast and the appearance of a tropical poikilotherm species Argonauta argo in these coasts is discussed. This is the first record of Argonauta argo in the north-west Iberian Peninsula. A female of this species was captured alive near the surface at dusk on 22 December 2000 in the Ria de Aldán (42°15′N-08°48′W). The specimen, a mature female of 70 mm mantle length and 96 mm shell diameter, died 36 hours after introduction in the tank.

F Rocha, Á F González, M Segonzac and Á Guerra

Behavioural observations of the cephalopod Vulcanoctopus hydrothermalis.

Cahiers de Biologie Marine, 43 (3-4): 299-302, 2002.

A Guerra, M Pérez-Losada, F Rocha and A Sanjuan

Species differentiation of Sepia officinalis and Sepia hierredda (Cephalopoda: Sepiidae) based on morphological and allozyme analyses.

Journal of the Marine Biological Association of the United Kingdom, 81 (2): 271-281, 2001.


the first time on the bases of quantitative morphology and allozyme polymorphisms. Morphometric measurements and meristic counts of selected soft and hard (cuttlebone) body characters, with allozyme electrophoretic analysis are used. Samples were obtained from north-west Iberian Peninsula and Senegalese waters (West Africa). Significant differences in mantle width, arm and hectocotylus length, numbers of rows of reduced suckers on the hectocotylus and in most cuttlebone measurements were found. Canonical discriminant functions of cuttlebone measurements for males and females were calculated. Allozyme electrophoresis for 33 presumptive loci showed low levels of genetic variability and 13 diagnostic loci between the two Sepia taxa. The genetic identities (I) in pairwise comparisons of populations of both taxa were I=0.582-0.596, which are typical values for congeneric species. These congruent morphological and genetic results strongly suggest that S. officinalis and S. hierredda are different species.

A Guerra, F Rocha, A F González and L F Bückle

Embryonic stages of the Patagonian squid Loligo gahi (mollusca: Cephalopoda).

Veliger, 44 (2): 109-115, 2001.


The embryonic development of Loligo gahi was observed from 4-day-old eggs to natural hatching. Egg strands spawned in the Valparaíso Bay, Chile, were transported to an open system tank for incubation. Temperatures ranged from 12.9°C to 13.5°C, salinities from 34‰ to 35‰, and the photoperiod was 12L:12D. The period from spawning to hatching ranged from 30-35 days. The diameter of individual eggs ranged from 2.5-3.2 mm, and the dorsal mantle length of hatchlings varied from 2.6-3.1 mm. The pattern of chronological appearance of organs was quite similar to loliginid species previously examined (Loligo aff. gahi, Loligo bleekeri, Loligo pealei, Loligo vulgaris reynaudii, and Loligo forbesii). However, L. gahi had a different (faster) development time and a smaller embryo and hatchling size than L. bleekeri (Japan) and L. forbesii (eastern Atlantic Ocean). Differences (heterochronies) among species are discussed. Allometric growth of embryonic development in L. gahi using seven morphometric parameters was undertaken.

F Rocha, A Guerra and A F González

A review of reproductive strategies in cephalopods.

Biological Reviews of the Cambridge Philosophical Society, 76 (3): 291-304, 2001.


Cephalopod reproductive strategies are reviewed in order to clarify their current, confusing status. Based on the type of ovulation, spawning pattern and growth between egg batches or spawning periods, five comprehensive and flexible cephalopod reproductive strategies are defined. Accordingly, with these three factors the following classification is proposed. (a) Spawning once (formerly semelparity) consisting of simultaneous terminal spawning, with synchronous ovulation, monocyclic spawning and absence of growth between egg batches. (b) Spawning more than once (formerly iteroparity) including: (i) polycyclic spawning with egg-laying occurring in separate batches during the spawning season and growth occurring between production of egg batches and spawning seasons; (ii) multiple spawning, with group-synchronous ovulation, monocyclic spawning and growth between egg batches; (iii) intermittent terminal spawning, with group-synchronous ovulation, monocyclic spawning and no growth between egg batches; (iv) continuous spawning, with asynchronous ovulation, monocyclic spawning and growth between egg batches. Examples of species exhibiting each of these reproductive strategies are given. The large amount of inter-species variation in several life-history traits related to reproductive events is discussed.

M A Vega, F J Rocha and C Osorio

Compared morphometry of squid statoliths loligo gahi d’orbigny, 1835 (cephalopoda: loliginidae) of northern peru and Falkland Islands [Morfometría comparada de los estatolitos del calamar Loligo gahi d’Orbigny, 1835 (Cephalopoda: Loliginidae) del norte de Perú e islas Falkland].

Investigaciones Marinas, 29 (1): 3-9, 2001.


A total of 241 statoliths were analyzed: 141 belonging to Loligo gahi from the Northern Perú (70 left statoliths and 71 right statoliths) corresponding to 34 males and 47 females, and 100 from the Falkland Islands (50 left statoliths and 50 right statoliths) corresponding to 35 males and 23 females. Total length (TL), dome length (DL) and face length (FL) were measured, determining in each specimen the mantle dorsal length (ML) and sex. The measures became quotients of ML, and were compared using discriminant analysis. Significant differences between the left statolith and the rigth statolith were not observed in either sex, reason why those of the right hand side were compared. Significant differences between males and females from the North of Perú were found as well as between both sexes from those of the Falkland Islands. There were also significant differences for individuals of the same sex between both zones. The meaning of the differences found between L. gahi statoliths from Perú and Falkland Islands are being discussed.

M Vecchione, R E Young, A Guerra, D J Lindsay, D A Clague, J M Bernhard, W W Sager, A F Gonzalez, F J Rocha and M Segonzac

Worldwide observations of remarkable deep-sea squids.

Science, 294 (5551): 2505-2506, 2001.

F Rocha, A Guerra, R Prego and U Piatkowski

Cephalopod paralarvae and upwelling conditions off Galician waters (NW Spain).

Journal of Plankton Research, 21 (1): 21-33, 1999.


A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 μm mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). The Rhynchoteuthion paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW).

F Rocha and A Guerra

Age and growth of two sympatric squid Loligo vulgaris and Loligo forbesi, in Galician waters (north-west Spain).

Journal of the Marine Biological Association of the United Kingdom, 79 (4): 697-707, 1999.


Age and growth of Loligo vulgaris and L. forbesi were studied by the examination of growth increments in 96 and 135 selected (white zone <10%) statoliths, respectively. Squid were obtained by monthly sampling from the catches of commercial trawling and hand-jigs in Galician waters (north-west Spain) between February 1991 and October 1993. Mantle length (ML) of L. vulgaris ranged from 70 to 480 mm and varied between 70 and 685 mm in L. forbesi. A negative allometry between statolith length and ML or body weight (BW) was found in both species. Sexual dimorphism was apparent in both species, males grew faster and longer than females. The statolith analysis suggests that growth patterns of L. vulgaris and L. forbesi in Galician waters are different. The exploited population of L. vulgaris was composed of two groups: one formed by individuals hatched in winter-spring and another by specimens hatched in summer-autumn. Squid hatched in winter spring reached larger sizes at the same age than those hatched in summer-autumn. These two groups were also observed in L. forbesi. However, squid of this species hatched in winter-spring were smaller than those hatched in summer-autumn at the same age. Reasons for this discrepancy are discussed. The life span of L. vulgaris was about one year whereas the life span of L. forbesi extended to 18 months.

F Simón, F Rocha and A Guerra

The small-scale squid hand-jig fishery off the northwestern Iberian Peninsula: Application of a model based on a short survey of fishery statistics.

Fisheries Research, 25 (3-4): 253-263, 1996.


A small-scale squid hand-jig fishery targeting the squids Loligo vulgaris and Loligo forbesi exists in the northwestern Iberian Peninsula. Its importance is evaluated using a model based on a short survey of fishery statistics. A total of 46 ports in Galicia operate this fishery. These ports were classified into three categories, according to characteristics relevant to the length of season in the fishery. Aguiño, Cedeira and Mugardos were selected as «model ports» for each of the three categories. The catch per unit effort and total catch were estimated for each of these model ports. Total catch for each port was estimated taking into account the catch obtained in each model port multiplied by a suitable correction factor based on the number of boats in each port. The ports of each of the three categories were considered separately. Thus we can obtain the total catch of the 46 Galician ports where this fishing activity takes place. It was calculated that the small-scale hand-jig fishery unloaded 282 t of squid in Galicia in 1992. The accuracy of the model based on a short survey of fishery statistics was tested by comparing estimates of catches with real squid landing data recorded in Aguifio in 1992. It was observed that the difference between the estimates (15.5 and 14.6 t, respectively) was 5.8%. Information on the characteristics of this fishery, seasonality, type and the number of fishing boats is included in this paper, which represents the first step towards assessing the magnitude of the squid resource in the hand-jig Galician fishery. © 1996 Elsevier Science B.V. All rights reserved.

F Rocha and A Guerra

Signs of an extended and intermittent terminal spawning in the squids Loligo vulgaris Lamarck and Loligo forbesi Steenstrup (Cephalopoda: Loliginidae).

Journal of Experimental Marine Biology and Ecology, 207 (1-2): 177-189, 1996.


The reproductive pattern of Loligo vulgaris and Loligo forbesi was studied on the basis of gonad maturation, mating and spawning in males and females of both species which were present off the northwest coast of Spain (Galicia), between February 1991 and February 1993. The mature females of both species have several modes of egg sizes and developmental stages within the ovary. Several signs indicate that both female Loligo vulgaris and L. forbesi undergo partial ovulation at the time of spawning, the spawning period being relatively long, although in no case representing the greatest fraction of the animal’s life before death. Egg-laying occurring in separate batches and somatic growth between egg batchs has not been observed. This reproductive pattern is defined as intermittent terminal spawning. Some other terms describing different cephalopod reproductive strategies are also defined.

A Guerra, P Sánchez and F Rocha

The Spanish fishery for Loligo: recent trends.

Fisheries Research, 21 (1-2): 217-230, 1994.


The Spanish fishery for the loliginid squids Loligo vulgaris and Loligo forbesi is described, with particular emphasis on the period 1983-1991. During this period the landings of squid in Spain stayed at a relatively constant level of around 2200 t. The value of the Spanish squid landings increased throughout the 1980s and amounted to £9.7 million in 1991. The two species of squid are not treated separately in the official statistics, and therefore the percentage corresponding to each is unknown; nevertheless, in the maritime regions of the Mediterranean, L. vulgaris is practically the only species landed, while in Atlantic regions, both are landed, although L. vulgaris is more abundant than L. forbesi. Particular attention is paid to the analysis and description of fisheries and squid landings in Galicia (northwest Spain) and Catalonia (northeast Spain), during the period 1980-1991. In both regions, part of the landings correspond to trawling and purse-seine fisheries targeting finfish, where squid is caught as a by-catch. There are also important seasonal artisanal fisheries where the target species is squid. Landings have shown a marked seasonality, being more plentiful in summer and autumn. This resource does not show signs of overfishing. The present methods of fishing management are discussed, and proposals are put forward to modify some of these in order to avoid catching immature individuals of less than 200 mm mantle length. © 1994.

A Guerra and F Rocha

The life history of Loligo vulgaris and Loligo forbesi (Cephalopoda: Loliginidae) in Galician waters (NW Spain).

Fisheries Research, 21 (1-2): 43-69, 1994.


The population biology of Loligo vulgaris and Loligo forbesi in Galician waters is described based on monthly samples from the fishery obtained during the period February 1991-June 1992. Maturity was assessed using a maturity scale and indices. The estimated number of oocytes in mature females varied from 782 to 21 885 in L. vulgaris and from 1317 to 14 956 in L. forbesi, and showed a slight positive correlation with the length of the mantle (ML) for both species. Oocytes in the ovaries fall into three discrete size classes, which suggests that L. vulgaris and L. forbesi are intermittent or multiple spawning species. In L. vulgaris males mature at two different modal sizes, hence perhaps at two different ages, while in L. forbesi this occurs in both males and females. Males mature earlier in the season than females in both species. The maximum number of spermatophores found was 1010 and 1000 in two L. vulgaris males with 119 mm and 400 mm ML respectively, and 1035 in a L. forbesi male with 150 mm ML. In both species, spermatophore length increases with ML. Loligo forbesi males maturing at a larger size produce fewer but larger spermatophores than those maturing at a small size. Loligo vulgaris spawn throughout the year, but the period of more intensive spawning extends from December to April. The breeding season of L. forbesi extends from December to May, the more intensive spawning extending from December to February. Sex ratios were variable for both species. Age and growth for both species and sexes were estimated by examining growth increments in the statoliths. Like-sized individuals had different ages in both species. The life span of L. vulgaris was estimated at about 1 year while L. forbesi seems to reach an age of 15-16 months. A list of prey species found in gastric contents of both species is given. The diet of L. vulgaris comprises fish (86.8%), cephalopods (6.0%), crustaceans (3.0%) and polychaetes (1.8%), and the diet of L. forbesi includes fish (75.6%), crustaceans (18.5%) and cephalopods (4.4%). © 1994.

F Rocha, B G Castro, M S Gil and A Guerra

The diets of Loligo vulgaris and L. Forbesi (Cephalopoda: Loliginidae) in Northwestern Spanish atlantic waters.

Sarsia, 79 (2): 119-126, 1994.


The stomach contents of 723 Loligo vulgaris and 440 Loligo forbesi caught in the northwestern Spanish Atlantic waters have been examined. The diets of both species are described and compared. Loligo vulgaris shows 28 different types of prey belonging to four groups (Teleostei, Crustacea, Cephalopoda and Polychaeta) and Loligo forbesi 27 different types of prey belonging to three groups (Teleostei, Crustacea and Cephalopoda). Both species catch similar prey species but in different proportions. Cannibalism was observed in both species. Estimated prey sizes were smaller than squid sizes. No differences in feeding habits of males and females of both species were observed, but females seem to increase food intake during maturation. No significant changes were found in the diet of Loligo vulgaris within the size (DML) range studied (65-465 mm). Importance of cephalopods increased and importance of fish decreased in the diet of Loligo forbesi with growth (65-685 mm). Diet and food intake varied with seasons in both species. Diets of both squids were significantly different. © 1994 Taylor & Francis Group, LLC.