Raúl Pérez-González

THE SIZE AT MATURITY OF THE BROWN CRAB CALLINECTES BELLICOSUS (DECAPODA, PORTUNIDAE) IN THE GULF OF CALIFORNIA

This study describes the size (carapace width, CW) at maturity of Callinectes bellicosus (Stimpson, 1859) based on samples from a coastal lagoon in the southern Gulf of California. The study was conducted since knowledge of the species in particular and the genus in general on the Pacific coast is scarce or non-existent and size at maturity is a key biological parameter for fisheries management. The collection of statistics on the crab fishery began in 1982, but landings of crab from the fishery increased exponentially until 2003. Samples were collected at the mouth of the lagoon and in the inside lagoon. A total of 651 brown crabs, including 255 females and 396 males, were processed from both sites. The crabs from the coastal lagoon showed a marked segregation of the sexes. In all, 73% of the crabs from the inside lagoon were males, and 71% of the crabs from the mouth of the lagoon were females. Immature females were predominant (78% of all females) in the inside lagoon, whereas mature females were predominant (81% of all females) at the mouth of the lagoon. Segregation according to the size at maturity was observed. The size at maturity was greater in the inside lagoon (114.08 mm CW) than at the mouth of the lagoon (103.73 mm CW). The pooled size at maturity was 107.78 mm CW. This report presents the first information on segregation by sex and maturity stage in any Callinectes species from the Mexican Pacific coast. These findings are important not only for fisheries management but also for the general biological knowledge of Callinectes species. We concluded that this study offers an improved approach for evaluating fisheries management, at least for the species studied here.

The interannual variability of size at maturity of the brown crab Callinectes bellicosus Stimpson, 1859 (Brachyura, Portunidae) in the Gulf of California

This study examines how the size at maturity (CW 50% ) of Callinectes bellicosus Stimpson, 1859 is affected by environmental variability and by the source of the data. The samples were obtained from a coastal lagoon in the eastern Gulf of California between 2000 and 2003, and in 2011. To explore for interannual variation in environmental conditions, an extended negative power-law model was used, with SSTa as the annual sum of monthly sea surface temperature anomalies and Chl-a as the monthly chlorophyll a mean in a year. The interannual variability in the CW 50% of C. bellicosus was also calculated. We found that the percent of mature female drives inter-annual variability in CW 50% and that the addition of Chl-a to the model does not contribute further to the explanation of this phenomenon. The hypothesis that environmental variations affect the reproductive dynamics of the stocks needs to be tested in this species in another area.

Catch composition of the spiny lobster Panulirus gracilis (Decapoda: Palinuridae) off the western coast of Mexico

The lobster fishery in the Gulf of California and the south-central region of the western coast of Mexico consists of small-scale artisanal activity supported by Panulirus gracilis and P. inflatus, with an annual average catch of 132 ton. The present study analyzes the landing composition of this fishery and the population structure of P. gracilis. Carapace lengths (CL) for this species ranged from 35 to 125 mm, and the most frequent sizes were between 60 and 85 mm. The size distribution was approximately normal. This implies that the fishery is composed of several size classes, with annual recruitment to the fishing areas. For the 1989-1990 and 1990-1991 fishing seasons, the mean monthly sizes of males were between 70.18 ± 11.74 and 81.11 ± 6.76 mm CL, whereas females averaged from 73.60 ± 8.95 to 80.28 ± 7.53 mm CL. Power-law relationships between carapace length (CL in mm) and total weight (TW in g) were determined, resulting in the following equations: PT = 0.0021 CL 2.7689 for males and PT = 0.0009 CL 3.0038 for females. During certain periods of the year, males dominated the catch; however, the overall annual male:female ratio was near 1:1.

Analysis of crab size structure and the fishing effort applied to a crab fishery in northwest Mexico

The fishing effort of a Sinaloa crab fishery in the Gulf of California in 2014 was analysed based on fishermen’s interviews, official catches and permits, and information from a sample of fishing logbooks from five fishery cooperatives operating in four coastal lagoons that contained the daily catch from individual fishing trips. Unauthorized gear, a double-ring net (DR), was used most frequently (>70% of the fishers) for crab fishing, although authorized single-ring nets and Chesapeake traps (CT) were also used with low frequency. The estimated fishing effort was 641 boats/day in the four coastal lagoons, which was 34% more than authorized, and 818 boats/day were employed in all of Sinaloa. A total of 57 479 fishing gears were estimated for the study area, which was 49.9% greater than the maximum authorized number, and 80 822 nominal fishing gears were estimated for the entire Sinaloa crab fishery, 14.15% more than the total gear limit (70 800). The size of the mesh used in the gear was smaller than the authorized limit of 76 mm, and >50% of the catches included crabs of unlawful size. It is argued that the effort must be regulated in terms of the number of vessels, per unit time, and not the number of gears. The information from this study demonstrates a failure to monitor compliance with current regulations and thus means that other strategies for the sustainable management of the fishery, such as co-management, should be tested.

Catch—Maximum Sustainable Yield Method Applied to the Crab Fishery (Callinectes spp.) in the Gulf of California

ABSTRACT The objective of this study was to determine the maximum sustainable yield (MSY) of the crab fishery in the Gulf of California by applying the catch-MSY method. This fishery occurs in two states—Sonora and Sinaloa, along the mainland coast of the Gulf of California—and involves two species: Callinectes hellicosus and Callinectes arcuatus. The main species supporting the fishery in both states is C. bellicosus, whereas C. arcuatus accounts for 5% of crab catches in Sonora and 20%–30% in Sinaloa. The catch-MSY method uses a set of viable r–k combinations to approximate MSY. The r–k combinations are the carrying capacity k and the maximum rate of population increase r for a given stock in a given ecosystem, which are required in most production models, such as the Schaefer model, to estimate MSY. Prior carrying capacity in this study was set arbitrarily from the maximum catches in a series evaluated to 100 times the maximum catch. This range ensures the real carrying capacity could be determined if catches were at MSY sometime during the period evaluated. Maximum potential could have been realized since 2006 for the Sinaloa stock and since 1996 for the Sonora stock. The evidence for these facts is that the catch per unit of effort decreased, and reductions were observed in the mean size of individuals; these changes occurred in the Sinaloa crab fishery. All methods devoted to management procedures of fisheries stocks entail a number of criticisms, and estimations of carrying capacity and stock biomass are costly; however, because sustainable fisheries are desired and data-poor stocks are common, a simple method like catch-MSY has proved be useful in the management of the crab fishery in the Gulf of California.

Size of structure and biometric relationships of the Grapsus grapsus rock crab on the Lobos, Venados, and Pájaros Islands, Sinaloa, Mexico

Background. Artisan fishermen along the southern Sinaloa coast catch alternative species, for example the Grapsus grapsus rock crab without biological and fishing controls, when their catches are reduced or when the season for catching certain fish has ended. Goals. We analyzed the size structure and biometric relationships of G. grapsus on Lobos, Venados, and Pájaros Islands of Mazatlán Bay, Sinaloa, Mexico. Methods. The cephalothorax width (CW) and weight (W) were analyzed during a one-year period (March 2012-February 2013). Results. 926 organisms were collected (519 males y 407 females). Pájaros Island had the greater percentage (37.4%) of collected organisms, followed by Lobos (34.2%), and Venados (28.4%) Islands. The greatest values were CW=74.5 mm recorded at Pájaros Island and W = 138.2 g at Venados Island and the lowest values were CW=13.9 mm at Pájaros Island and BW =1.1 g at Lobos Island. Means of CW and W were 41.4 mm and 31.5 g, respectively. The means of CW and W were statistically different between the islands (CL, p = 0.009; W, p < 0.015). Conclusions. High determination coefficients between the variables were obtained, indicating isometric growth. Specimens of G. grapsus increase their size quickly and their weight very slowly.

Potential distribution of Geoduck clam Panopea globosa of the Gulf of California in a climate change Model

El cambio climatico ha roto el equilibrio natural y se ha modificado el estado de salud de las diferentes especies comerciales como la almeja de sifon. Por lo tanto, el objetivo del presente estudio fue pronosticar la distribucion de almeja de sifon Panopea globosa del Golfo de California en el ano 2050 ante un escenario de cambio climatico. Se uso el modelo de maxima entropia (MaxEnt) utilizando 12 variables ambientales que afectan la distribucion desde el punto de vista termico, quimico y biologico. El modelo de MaxEnt predijo el habitat potencial adecuado para P. globosa con altas tasas de exito ( Area Under the Curve [AUC] = 0.995). El habitat mas favorable de P. globosa se encuentra en Guaymas, Sonora, debido a la surgencia de nutrientes que benefician la produccion de clorofila-a. Para el ano 2050, el modelo MaxEnt pronostico que en Sonora se presentara una reduccion hacia la costa sur. En Santa Rosalia e Isla San Marcos, Baja California Sur, las probabilidades disminuyen de 0.70 a 0.04. Los actuales sitios de captura se notaran alterados con posibles afectaciones sociales y economicas en las comunidades litorales. La conclusion es que el estudio resulta importante para la administracion de recursos pesqueros, ya que en un escenario de cambio climatico los sitios de captura pueden modificarse.

Occurrence of Panulirus inflatus (Decapoda Palinuridae) pueruli in the southeastern Gulf of California, Mexico

This study presents results on the collection of Panulirus inflatus pueruli in seaweed (GuSi; set at the surface) and crevice (Booth: set on the bottom) collectors from April to December 1998 in waters of the southeastern Gulf of California, Mexico. The collectors were deployed at two sites in Mazatlan Bay. A total of 15 pueruli and 26 post-pueruli were collected, of which 4 postpueruli were found in crevice collectors from 10 inspections. Examination of the crevice collectors was difficult because weather conditions made sampling problematic during the year in this zone. Seaweed collectors caught 37 pueruli in 91 observations. Most of the pueruli from these collectors were caught between April and June, with a peak settlement in May (19) and a mean surface water temperature of 24.4°C. The highest catch per unit of effort was 1.36 pueruli per collector per week in May, followed by April (0.33) and June (0.31). Statistical tests showed no significant differences among the moon phases, although the number of pueruli was higher during the first quarter. This is the first record of P. inflatus pueruli in the southeastern Gulf of California on specifically designed collectors.