Biology of the red mullet mullus surmuletus (mullidae) off the Canary Islands, Central-East Atlantic

The biology of red mullet Mullus surmuletus was studied from collections taken off the Canary Islandsbetween January 1991 and September 1993. Total length ranged from 12 to 33 cm, mainly between 15 and 21cm. Males ranged from 14 to 26 cm and females from 14 to 33 cm. Females dominated the larger size-classes (>18 cm). The overall ratio of males to females was 1:2.3. The reproductive period extended from February toMay, spawning peaking in March and April. The total length at 50% maturity was 16.6 cm for the whole population.The length-mass relationship for all individuals can be described by the parameters a = 0.0074 and b = 3.1826. Fish aged 0.8 years were present in the samples. The parameters of the Von Bertalanffy growth equation obtained for all individuals were: L‡ = 35.71 cm and k = 0.22.year-1. Significant differences were found in the growth parameters between males and females. The rates of total mortality Z, natural mortality M and fishing mortality F were 1.25, 0.55 and 0.70.year-1 respectively. The estimated total length at first capture was 15.74 cm

Age and growth of black seabream Spondyliosoma cantharus (Linnaeus, 1758) (Sparidae) off the Canary Islands

The authors determined the age and growth of black seabream Spondyliosoma cantharus (Linnaeus, 1758) caught off the Canary Islands, using the otolith interpretation method. Annual rings are clear in the otolith cross-sections. Two rings, one associated with fast-growing periods (summer) and the other with slow-growing periods (winter) are deposited each year on the otoliths. The specimens ranged from 9.4 cm - 38.6 cm in total length, with ages of 0-9 years. Individuals grew quickly until the third year of life, at which they had reached more than 50 % of their maximum length. The Von Bertalanffy growth curve parameters were: L∞ = 44.09 cm, K = 0.23 year⁻¹, and t0 = -0.34 years. The growth found for this sample of black seabream is very similar to that reported for the species in other regions.Se determinan la edad y el crecimiento de la chopa Spondyliosoma cantharus (Linnaeus, 1758) de las islas Canarias por interpretación de los anillos visibles en los otolitos. Los anillos de crecimiento anuales se observan con claridad en las secciones transversales de los otolitos. Cada año se forman dos anillos, uno de crecimiento rápido en los meses de verano y otro de crecimiento lento durante el periodo invernal. Los ejemplares, de tallas que oscilan desde 9,4 hasta 38,6 cm de longitud total, presentan edades comprendidas entre 0 y 9 años. El crecimiento de los individuos es rápido durante los primeros años de vida, alcanzando al tercero más de la mitad de su talla máxima. Los parámetros de la curva de crecimiento de Von Bertanlanffy son: L∞ = 44,09 cm, K = 0,23 años⁻¹ y t0 = -0,34 años. El crecimiento de la chopa en las islas Canarias es similar al observado para la misma especie en otras regiones.Instituto Español de Oceanografí

State of exploitation of the black seabream, Spondyliosoma cantharus (Linnaeus, 1758), off Gran Canaria (Canary Islands)

En el presente trabajo se evalúa el estado de explotación de la chopa Spondyliosoma cantharus (L., 1758) en aguas de Gran Canaria (islas Canarias) mediante el análisis de cohortes sobre distribuciones de tallas. Para llevar a cabo el análisis se dispuso de 30 068 ejemplares procedentes de pescas comerciales realizadas entre enero de 1994 y diciembre de 1996. La chopa, especie común en las capturas demersales efectuadas por la flota artesanal en Gran Canaria, se pesca principalmente con nasa y, de forma ocasional, con palangre. Las tallas de los individuos capturados están comprendidas entre 8 y 40 cm de longitud total. La nasa incide sobre ejemplares de todas las clases de tallas, principalmente de 20-22 cm, y el palangre sobre ejemplares de 20 a 40 cm, principalmente de 24-26 cm. La estrategia de pesca actual genera una situación de sobrepesca en crecimiento. Un cambio en el esquema, basado en la reducción de la mortalidad pesquera para la nasa, incrementaría de manera significativa el rendimiento y la biomasa de reproductores.The study examines the state of exploitation of the black seabream, Spondyliosoma cantharus (L., 1758), off Gran Canaria (Canary Islands) using a length cohort analysis based on data from 30 068 individuals obtained from commercial catches between January 1994 and December 1996. The black seabream, a common species in the demersal catches of the artisanal Gran Canaria fishery, is mainly captured with traps, and occasionally with longlines. Total length of individuals ranged from 8 cm to 40 cm. Specimens from the subgroup caught by traps ranged from 8 cm to 40 cm, but were mostly 20-22 cm; the longline subgroup ranged from 20 cm to 40 cm, with most individuals measuring 24-26 cm. The current fishery strategy produces a situation of overexploitation; a change, reducing fishing mortality resulting from trap use, would significantly increase both the yield and the spawning stock biomass.Instituto Español de Oceanografí

Reproductive biology of the sand smelt Atherina presbyter Cuvier, 1829 (Atherinidae) off Gran Canaria (Canary Islands)

Se estudiaron 1 028 ejemplares de guelde blanco Atherina presbyter Cuvier, 1829 capturados alrededor de la isla de Gran Canaria (islas Canarias) durante el periodo comprendido entre julio de 1995 y junio de 1996. Las tallas oscilaron entre 14,6 mm y 115,5 mm de longitud total. La proporción entre sexos no presentó diferencias significativas con la relación teórica 1:1. El periodo reproductor se situó entre febrero y junio, con un máximo de actividad gonadal en abril-mayo. Las tallas medias de primera maduración y de maduración masiva se alcanzaron, respectivamente, a los 67,7 mm y 94,9 mm en los machos y a los 65,3 mm y 92,6 mm en las hembras; tampoco en estos valores medios las diferencias entre los dos sexos se mostraron estadísticamente significativas.Sand smelt Atherina presbyter Cuvier 1829 (N = 1 028) caught off Gran Canaria (Canary Islands) between July 1995 and June 1996 were studied. The size range was 14.6 mm to 115.5 mm total length. The ratio of males to females was not significantly different from 1:1. The reproductive period extended from February to June, with an April-May peak in spawning activity. Mean total lengths at 50 % and 95 % maturity were 67.7 mm and 94.9 mm for males, and 65.3 mm and 92.6 mm for females, although these different values between the sexes were not statistically significant.Instituto Español de Oceanografí

Growth of the chub mackerel Scomber japonicus (Houttuyn, 1782) off the Canary Islands determined by length-frequency analysis

The growth of the chub mackerel Scomber japonicus (Houttuyn, 1782) off the Canary Islands was determined by length-frequency analysis. The total length was measured in 3858 individuals captured south-west of Gran Canaria (Canary lslands) from March 1988 to July 1990. The length range was wide (13-48 cm total length) and the frequencies were very variable. The class modes, identified by using the method of Bhattacharya (1967), corresponded to the age-groups 0-5 years. The value of the theoretical maximum length obtained by means of the method of Wetherall, Polovina and Ralston (1987) was 47.3 cm. The values of the parameters of the seasonally oscillating Von Bertalanffy growth equation, determined by the method of Pauly and David (I981), were L∞= 49.50 cm, k = 0.23 year˄-1, C = 0.650 and WP = 0.800. The length frequency analysis provided very satisfactory results for the Canary Islands chub mackerel. These results were very similar to those obtained by reading otoliths.Se determinó el crecimiento de la caballa Scomber japonicus (Houttuyn, 1782) de las islas Canarias a través del análisis de las frecuencias de tallas. La longitud total fue medida en 3858 ejemplares capturados al suroeste de Gran Canaria (islas Canarias) entre los meses de marzo de 1988 y julio de 1990. El rango de tallas fue amplio (13-48 cm de longitud total) y su abundancia relativa variable. Las tallas modales discriminadas mediante el método de Bhattacharya (1967) correspondieron a los grupos de edad de 0 a 5 años. El valor de la longitud máxima teórica, obtenida por aplicación del método de Wetherall, Polovina y Ralston (1987), fue 47,3 cm. Los valores de los parámetros de la ecuación de crecimiento estacional oscilatorio de Von Bertalanffy, obtenidos por el método de Pauly y David (1981), fueron L∞= 49,50 cm, k = 0,23 año˄-1, C = 0,650 y W = 0,800. Los métodos de análisis de frecuencia de tallas ofrecieron resultados muy satisfactorios para la caballa de las islas Canarias. Dichos resultados fueron muy similares a los obtenidos por lectura directa de los otolitos.Instituto Español de Oceanografí

New and rare records of teleost fishes from the Cape Verde Islands (eastern-central Atlantic Ocean)

As a result of six exploratory surveys and several opportunistic catches in the Cape Verde Islands from a few metres to about 1000 m of depth, a list of 66 species of teleost fishes is given, six of which are first records from the archipelago: Gnathophis mystax (Congridae), Nezumia africana, Nezumia duodecim (Macrouridae), Ectreposebastes imus (Scorpaenidae), Paraliparis sp. (Liparidae) and Lappanella fasciata (Labridae). Additionally, data on six poorly-known species is also given: Myroconger compressus (Myrocongridae), Myrichthys pardalis, Phaenomonas longissima (Ophichthidae), Sphagemacrurus hirundo (Macrouridae), Gadella imberbis and Physiculus cyanostrophus (Moridae). Data includes distribution, habitat, morphometry and reproduction.Six campagnes exploratoires ainsi que quelques captures opportunistes réalisées de quelques mètres jusqu’à environ 1000 m de profondeur aux îles du Cap-Vert ont permis d’établir une liste comprenant 66 espèces de poissons téléostéens. Six espèces sont signalées pour la première fois aux îles du Cap-Vert : Gnathophis mystax (Congridae), Nezumia africana, Nezumia duodecim (Macrouridae), Ectreposebastes imus (Scorpaenidae), Paraliparis sp. (Liparidae) et Lappanella fasciata (Labridae). La présence de six autres espèces mal connues est confirmée pour cet archipel : Myroconger compressus (Myrocongridae), Myrichthys pardalis, Phaenomonas longissima (Ophichthidae), Sphagemacrurus hirundo (Macrouridae), Gadella imberbis et Physiculus cyanostrophus (Moridae). Les données présentées concernent la distribution, l’habitat, la morphométrie et la reproduction.Postprin

The striped soldier shrimp Plesionika edwardsii (Crustacea:Decapoda:Pandalidae) from the cape Verde Islands

This study is part of the PROACTIVA 1-2 (2009-2012) and MARPROF-CV (2010-2014) projects, in the framework of the Canary Islands Government and UE PCT MAC 2007-2013 programmes respectively. Research has mainly focused on the stock assessment of the striped soldier shrimp, Plesionika edwardsii (Brandt, 1851), because it has shown moderate to high levels of fishing yield and abundances compatible with the development of a new sustainable fishery in the Cape Verde Islands. Cruises took place on board the R/V Prof. Ignacio Lozano. Four 15-day surveys have been conducted to date: Cabo Verde 2010-04 (April 2010), Camar˜ao-1 (November 2011), Camar˜ao-2 (Mars 2012) and Camar ˜ao-3 (July 2012). An innovative fishing gear so-called multiple semi-floating shrimp trap (MSFST) was used. Each fishing line was composed by 40-65 traps operating around 2.4 m above the seafloor, using Decapterus macarellus (Carangidae) as unique bait of the traps. Fishing depth was 66-458 m, and efective fishing time was 16-18 h. Each trap was attached to the main bottom line every 15 m, and the maximum attraction of this bait was established to be 100 or 150 m, according to the experience gained from the local fishery for deep-sea lobsters. So density by area was calculated assuming two different areas of attraction of the fishing gear. Initial biomass was estimated from depletion experiments at different abundance stations by applying the Leslie & Davis (1939) method, modified by Ricker (1975). Each fishing operation was classified according to its yield (CPUE in g/trap/night). The potential fishing planar area was estimated between the isobathymetric lines between 90 and 220 m. Total biomasses (Bt) were calculated from areas (km2) and mean minimum/maximum densities (kg/km2). Maximum sustainable yield (MSY) was estimated from Bt using the Beddington and Cooke (1983) model by entering natural mortality (0.6), growth rate (0.53 year�1) and recruitment age (1.32 year), which are the parameters for this target species published for the Canaries. These parameters estimate a biological exploitation rate ( ) of 0.262. Interpolations were applied to estimate MSY for insular stocks representing lesser than 5% of the total fishing grounds for this species in the archipelago. The MSY estimated by depletion were 30.5 tons/year for the stock of S˜ao Vicente, Santa Luzia, Ilheus and S˜ao Nicolau, 10 tons/year for the stock of Santiago, 138.8 tons/year for the stock of Boa Vista and Maio, and 5.6 tons/year for the stock of Sal. The small stocks estimated by interpolation were: 4.5 tons/year for the stock of Santo Ant˜ao, 1.3 tons/year for the stock of Fogo, and 1.8 tons/year for the stock of Brava and Ilheus. In total, 192.5 tons per year was the total MSY for the striped soldier shrimp around the islands of the Cape Verde archipelago, occupying a total area of 1,918 km2 of new fishing grounds at between 90 and 220 m of depth. In comparison with the traditional bottom trap used in the Canary Islands, the innovative fishing gear MSFST were proved to be more selective for pandalid shrimps, minimizing the gear impact on the seafloor as well as the by-catch by reducing the discards. Depletion methods are based on the assumption of a closed system, that is with minimum or zero immigration between neighbouring areas. The straight forward decline of CPUEs obtained during the depletion experiments seems to confirm that P. edwardsii is a low mobility species, making this assumption valid at least during short-time periods. Because of the bathymetry profile of these islands,the depth range is from very close (few nautical miles in Santiago) to far away (10-12 n.m. in Boa Vista) to the coastline. Fishing effort should be controlled on the basis of quotas, number of fishing vessels and a precautionary approach in order to ensure that catching is commensurate with sustainable levels of exploitation. MSY estimates suggest that this new Capeverdean fishery should be carried out by specialized medium-sized fishing vessels. During the last decades a combination of shrimp trawling and industrial trapping activity has threatened over-exploitation in the Mediterranean fisheries targeting on P. edwardsii; currently the shrimp collapse has conducted to the decline of these fisheries. Can the Cape Verde regulatory bodies and all the stakeholders involved learn the lessons this teaches us about this resource management

By-catch composition of the striped soldier shrimp Plesionika edwardsii (Crustace: Decapoda: Pandalidae) experimental fishery in the Cape Verde Islands

This work focuses on the by-catch composition of Plesionika edwardsii experimental fishery in the Cape Verde Islands. Obtaining information on abundance, composition and lifecycle of species involved in this potential fishery is useful, in order to ensure its sustainable development under an ecosystem approach. The first step towards this goal is the description of catches. Four 15-day research surveys were conducted on board the R/V Prof. Ignacio Lozano: April 2010 (S˜ao Vicente and Santa Luzia islands), November 2011 (Santiago island), March 2012 (Boa Vista island,) and July 2012 (Sal and S˜ao Nicolau islands). The working depths were between 66 and 458 m depth. A standardized innovative fishing gear was used, so-called multiple semi-floating shrimp traps. Each fishing line was composed by 40-65 traps operating around 2.4 m above the seafloor, using Decapterus macarellus (Carangidae) as unique bait of the traps. Multiple semi-floating shrimp traps is a passive fishing system that allows catch and release sea significant part of the unwanted catches, as in the case of Chondrichthyes or Anguilliformes, reducing the fishing impact on non-target species. The main by-catch was composed of 53 species belonging to three groups including Chondrichthyes (three families and three species), Crustacea (11 families and 19 species) and Osteichthyes (15 families and 29 species). Plesionika edwardsii, the target species of this fishery, represented 97.8% of the catch in terms of abundance and 40.1% in biomass. By-catch represented 59.9% of total catch in terms of biomass. Osteichthyes (87.5%) were the dominant group and was represented by the following main families; Sparidae (33.9%), Moridae (32.5%), Muraenidae (32.5%), Scorpaenidae (9.9%) and Tetraodontidae (9.8%). Chondrichthyes (11.6%) were composed by Centrophoridae (65.3%) and Triakidae (34.1%). Finally, Crustacea (1.9%) were chiefly composed by Pandalidae (79.1%). However, different families represented by specific species were found to be dominant around each island. Sparidae were the dominant family represented by Pagellus acarne (46.2% of total by-catch) at S˜ao Vicente, and by Dentex macrophthalmus (42.6%) at Boa Vista. Tetraodontidae with Sphoeroides pachygaster (25.9%) and Sparidae with P. acarne (25.1%) were the co-dominant families in the by-catch around Santa Luzia. Muraenidae were the dominant family represented by Gymnothorax polygonius (69.4%) at Sal, and by Muraena helena (63.4%) at S˜ao Nicolau. Finally, Scorpaenidae with Pontinus kuhlii (22.3%) and Moridae with Physiculus cyanostrophus (22.1%) were the co-dominant families of the bycatch around Santiago. Acknowledgements: This study is part of the PROACTIVA 1-2 (2009-2012) and MARPROF-CV (2010-2014) projects, in the framework of the Canary Islands Government and UE PCT MAC 2007- 2013 programmes respectively

New and rare records of teleost fishes from the Cape Verde Islands (eastern-central Atlantic Ocean)

As a result of six exploratory surveys and several opportunistic catches in the Cape Verde Islands from a few metres to about 1000 m of depth, a list of 66 species of teleost fishes is given, six of which are first records from the archipelago: Gnathophis mystax (Congridae), Nezumia africana, Nezumia duodecim (Macrouridae), Ectreposebastes imus (Scorpaenidae), Paraliparis sp. (Liparidae) and Lappanella fasciata (Labridae). Additionally, data on six poorly-known species is also given: Myroconger compressus (Myrocongridae), Myrichthys pardalis, Phaenomonas longissima (Ophichthidae), Sphagemacrurus hirundo (Macrouridae), Gadella imberbis and Physiculus cyanostrophus (Moridae). Data includes distribution, habitat, morphometry and reproduction.Six campagnes exploratoires ainsi que quelques captures opportunistes réalisées de quelques mètres jusqu’à environ 1000 m de profondeur aux îles du Cap-Vert ont permis d’établir une liste comprenant 66 espèces de poissons téléostéens. Six espèces sont signalées pour la première fois aux îles du Cap-Vert : Gnathophis mystax (Congridae), Nezumia africana, Nezumia duodecim (Macrouridae), Ectreposebastes imus (Scorpaenidae), Paraliparis sp. (Liparidae) et Lappanella fasciata (Labridae). La présence de six autres espèces mal connues est confirmée pour cet archipel : Myroconger compressus (Myrocongridae), Myrichthys pardalis, Phaenomonas longissima (Ophichthidae), Sphagemacrurus hirundo (Macrouridae), Gadella imberbis et Physiculus cyanostrophus (Moridae). Les données présentées concernent la distribution, l’habitat, la morphométrie et la reproduction.S

By-catch composition of the striped soldier shrimp Plesionika edwardsii (Crustace: Decapoda: Pandalidae) experimental fishery in the Cape Verde Islands

This work focuses on the by-catch composition of Plesionika edwardsii experimental fishery in the Cape Verde Islands. Obtaining information on abundance, composition and lifecycle of species involved in this potential fishery is useful, in order to ensure its sustainable development under an ecosystem approach. The first step towards this goal is the description of catches. Four 15-day research surveys were conducted on board the R/V Prof. Ignacio Lozano: April 2010 (S˜ao Vicente and Santa Luzia islands), November 2011 (Santiago island), March 2012 (Boa Vista island,) and July 2012 (Sal and S˜ao Nicolau islands). The working depths were between 66 and 458 m depth. A standardized innovative fishing gear was used, so-called multiple semi-floating shrimp traps. Each fishing line was composed by 40-65 traps operating around 2.4 m above the seafloor, using Decapterus macarellus (Carangidae) as unique bait of the traps. Multiple semi-floating shrimp traps is a passive fishing system that allows catch and release sea significant part of the unwanted catches, as in the case of Chondrichthyes or Anguilliformes, reducing the fishing impact on non-target species. The main by-catch was composed of 53 species belonging to three groups including Chondrichthyes (three families and three species), Crustacea (11 families and 19 species) and Osteichthyes (15 families and 29 species). Plesionika edwardsii, the target species of this fishery, represented 97.8% of the catch in terms of abundance and 40.1% in biomass. By-catch represented 59.9% of total catch in terms of biomass. Osteichthyes (87.5%) were the dominant group and was represented by the following main families; Sparidae (33.9%), Moridae (32.5%), Muraenidae (32.5%), Scorpaenidae (9.9%) and Tetraodontidae (9.8%). Chondrichthyes (11.6%) were composed by Centrophoridae (65.3%) and Triakidae (34.1%). Finally, Crustacea (1.9%) were chiefly composed by Pandalidae (79.1%). However, different families represented by specific species were found to be dominant around each island. Sparidae were the dominant family represented by Pagellus acarne (46.2% of total by-catch) at S˜ao Vicente, and by Dentex macrophthalmus (42.6%) at Boa Vista. Tetraodontidae with Sphoeroides pachygaster (25.9%) and Sparidae with P. acarne (25.1%) were the co-dominant families in the by-catch around Santa Luzia. Muraenidae were the dominant family represented by Gymnothorax polygonius (69.4%) at Sal, and by Muraena helena (63.4%) at S˜ao Nicolau. Finally, Scorpaenidae with Pontinus kuhlii (22.3%) and Moridae with Physiculus cyanostrophus (22.1%) were the co-dominant families of the bycatch around Santiago. Acknowledgements: This study is part of the PROACTIVA 1-2 (2009-2012) and MARPROF-CV (2010-2014) projects, in the framework of the Canary Islands Government and UE PCT MAC 2007- 2013 programmes respectively