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Marine protected areas (MPA) gained wide acceptance as tools for restoring depleted species in the 1990's. MPA's in Mexico have failed to fulfill its management and conservation objectives because of its weakness of initial objectives, design, and level of enforcement.

A full analysis of the reproductive biology of the isopod Excirolana braziliensisRichardson 1912 was conducted in a sandy beach of Uruguay, located at the southernmost edge of its distributional range in the Atlantic Ocean. Reproductive and recruitment periods of E. braziliensiswere concentrated in austral summer. Females with oostegites appeared in November, whereas total biomass, individual sizes and fecundity of ovigerous females peaked between December and January. These concurrent traits were responsible for the significant peak of juveniles in January. The size at maturity was 9.88 mm. Four embryonic developmental stages were described and identified: mean length linearly increased from stages I to III, whereas dry weight exponentially decreased from stages I to IV. The high reproductive output (0.41–0.58), reported for the first time in this isopod, exceeds the rates documented for other isopods. Reproduction of E. braziliensisat the southern edge of its range is semelparous: females produce one brood during the reproductive season, exhaust their energy reserves during incubation, and probably die at the end of the reproductive season. A macroscale comparison suggests that E. braziliensisat the southern edge of its range counteracts its narrow reproductive period by a short incubation period with larger individual mature female and embryo sizes, higher fecundity and a higher percentage of ovigerous females than in subtropical and tropical populations. These extreme reproductive indicators could be attributed to the internal retention of embryos that assures offspring survival, coupled with a high adaptation capability to environmental variations across its range.

The present study evaluates the effects of an artificial freshwater discharge (Canal Andreoni) on the ecology of the ovoviviparous isopod Excirolana armata. Bimonthly, 17 environmental variables plus isopod abundance, biomass, fecundity, growth and mortality were compared between three sites: ?Barra del Chuy' (undisturbed), at 13 km from the canal, ?Coronilla' (moderately disturbed), at 1 km, and ?Andreoni' (grossly disturbed), at the canal mouth. Environmental (salinity, slope, beach width, and swash width) and some biological (isopod abundance, biomass and growth rates) variables significantly decreased towards Canal Andreoni. Salinity was the most important explanatory variable of spatial trends in isopod biomass. However, the reproductive output, fecundity, survival and individual weight were not affected, suggesting that E. armata is regulated by density-dependent and abiotic factors operating together: the former were more intense on undisturbed conditions, whereas the latter prevailed in impacted ones. Internal brooding counteracts the effect of fresh water, which explains the lack of effect of environmental harshness on reproductive traits.

Global concerns about the depletion of marine stocks have been widely documented in industrial fisheries. However, small-scale artisanal fisheries constitute a second component for the world fishery crisis, normally ignored or erroneously lumped into the industrial component. In this paper we first present a brief comparison between industrial and artisanal fisheries, highlighting the differences between them and the differential feasibility for implementing management options. We propose that industrial and artisanal fishery problems have to be treated separately and thus cannot be lumped into a single “fishing bag”. Among artisanal fisheries, we focus on coastal benthic shellfisheries, highlighting that their sedentary or sessile nature make them amenable to implement spatially-explicit management tools such as rotation of areas and territorial user rights (TURFs). Then, using long-term catch trends and selected examples, we demonstrate the power and validity of co-management for some Latin American shellfisheries, notably in Chile and Mexico, and stress the need to institutionalize the existent fishery knowledge. Several idiosyncratic properties of co-management in our Latin American examples have been useful to sustain the resources over time, including: (a) allocations of TURFs, (b) Community Fishery Quotas, which may be sub-allocated to families, (c) community-based and family-oriented sociological and organizational context of co-management, which may drive short and long-term market forces.Global concerns about the depletion of marine stocks have been widely documented in industrial fisheries. However, small-scale artisanal fisheries constitute a second component for the world fishery crisis, normally ignored or erroneously lumped into the industrial component. In this paper we first present a brief comparison between industrial and artisanal fisheries, highlighting the differences between them and the differential feasibility for implementing management options. We propose that industrial and artisanal fishery problems have to be treated separately and thus cannot be lumped into a single “fishing bag”. Among artisanal fisheries, we focus on coastal benthic shellfisheries, highlighting that their sedentary or sessile nature make them amenable to implement spatially-explicit management tools such as rotation of areas and territorial user rights (TURFs). Then, using long-term catch trends and selected examples, we demonstrate the power and validity of co-management for some Latin American shellfisheries, notably in Chile and Mexico, and stress the need to institutionalize the existent fishery knowledge. Several idiosyncratic properties of co-management in our Latin American examples have been useful to sustain the resources over time, including: (a) allocations of TURFs, (b) Community Fishery Quotas, which may be sub-allocated to families, (c) community-based and family-oriented sociological and organizational context of co-management, which may drive short and long-term market forces.

Chaceon notialis is a brachyuran crab inhabiting the continental slope (250-1,000 m) off Uruguay in the southwestern Atlantic Ocean, constituting one of the main exploited stocks of deep-sea red crab in the world. The objective of this paper was to estimate size at morphological and physiological sexual maturity in females of Chaceon notialis in Uruguayan waters. Crabs were obtained from commercial samples taken in 1997 and 1998. For each individual, carapace width (CW) was measured and morphological (abdomen width and vulval features) and physiological (ovarian maturity) reproductive indicators were examined in order to estimate the size at sexual maturity. As the existence of a terminal molt still cannot be confirmed in females of C. notialis, we tested the alternative hypotheses that females: (1) have indeterminate growth and (2) exhibit a terminal molt. Hypothesis 1 was evaluated by fitting the logistic maturity function that provides the CW50% of females with mature vulvae, whereas hypothesis 2 was evaluated through the analysis of CW frequency distributions of morphologically and physiologically mature females. In addition, 50 pairs of female spermathecae were examined to determine if insemination had occurred; the carapace hardness of the individuals concerned was also noted. Two patterns of vulval morphology in females of C. notialis were observed for the first time: immature or ttclosedtt vulvae, and mature or ttopenedtt vulvae, respectively. Estimations of size at sexual maturity differed according to the hypothesis evaluated: under the assumption that females continue growing after the pubertal molt, mean sizes at morphological and physiological maturity (CW50%) were estimated as 70.2 mm and 71.7 mm, respectively. Alternatively, if females have a terminal molt, mean (± SD) estimates were 91.5 ± 8.5 mm and 91.1 ± 8.0 mm, respectively. Both scenarios clearly suggest synchrony between vulval and ovarian maturity. The species displays a soft mating system and most mature postmolt females lacks seminal contents in their reservoirs, in spite of evidence of successful mating (abrasion marks). This suggests that, due to selective exploitation of males, sperm supply may have become a limiting resource for the reproductive output of the population. Under the terminal molt hypothesis, females at the pubertal moult will be the only individuals in the population contributing to reproduction. Taking into account these findings, we suggest that the current regulations are reassessed, including the use of the terminal molt scenario for fishery management because it provides a precautionary framework in a situation where the life history of the targeted stock is data-limited.

Abstract: Spatio-temporal variability in the length-weight relationship of four sympatric shrimp species (Farfantepeneus aztecus, F. brasiliensis, F. duorarum, andF. notialis) was evaluated in the Celestun lagoon, Mexico. Monthly samples were taken throughout 2 yr in three hydrological zones (seaward, middle, and inner) and climatic seasons (Nortes, Dry, and Rainy). Significant intraspecific and interspecific differences in the length-weight relationships were detected among climatic seasons and hydrological zones, reflecting positive allometric growth.F. notialis registered the highest condition (weight at length), followed byF. duorarum, F. aztecus, andF. brasiliensis. The lowest values in condition were consistently registered during Nortes and at the seaward zone. All species showed a pattern consistent with a density-dependent effect on condition, that is a negative correlation between individual mean weight and total relative abundance. The immediate implication for managing this important multispecific coastal artisanal resource that is supported by our study is the restriction of fishing effort in the seaward zone, mainly during the Nortes seasons.

We describe daily allocation patterns of fishing effort (hookah diving) of the artisanal fleet in San Felipe, Yucatan (Mexico), using catch, fishing effort, catch per unit of effort, variable costs, quasi rent and distance from port to four fishing grounds as performance variables. Two vessel categories were defined by the presence/absence of a LOng RAnge Navigation (LORAN) system. Hookah divers caught a daily average of four species in 95% of the trips, thus precluding the quantification of effective fishing effort allocated by species. Highest catches and quasi rent were mainly obtained on Thursdays and Fridays, coinciding with the highest catches of Octopus mayaand spiny lobster (making up 50% of the total economic revenue) on Fridays in 3 of the 5 weeks analysed. An upper ceiling of daily catch per diver occurred close to the weekend, suggesting a limited capacity in terms of handling time and diving hours, and also a catch level that fulfills daily economic expectations. Both LORAN and non-LORAN vessels preferred to work the nearest ground to port, in spite of higher yield and economic rent from more distant grounds. Nonlinear modelling of fishing effort allocation showed distance from port as the key decision factor. Generalized linear modelling (GLM) revealed significant effects of vessel type and fishing ground, with LORAN vessels having significantly higher catch rates and tending to allocate more effort to distant grounds than vessels without LORAN. GLM performed by species corroborated that Friday was the most productive day concerning spiny lobster and octopus. This day effect in the most valued species also suggests that pressure for higher economic benefits occurs before diminishing (Saturday) or ceasing (Sundays) fishing activities.

Abstract In Latin America the small-scale fishery ofmarine benthic invertebrates is based onhigh-value species. It represents a source offood and employment and generates importantincomes to fishers and, in some cases, exportearnings for the countries. In the review, wedefine 2 key concepts: small-scale fishery andco-management. We address the temporalextractive phases which Latin Americanshellfish resources have experienced, and thecorresponding socio-economic and managerialscenarios. We include 3 study cases in whichco-management and field experimentation havebeen used on different temporal and spatialscales: (a) the muricid gastropod (Concholepas concholepas) in Chile; (b) theyellow clam (Mesodesma mactroides) inUruguay; and (c) the spiny lobster (Panulirusargus) in Mexico. We demonstratethat co-management constitutes an effectiveinstitutional arrangement by which fishers,scientists and managers interact to improve thequality of the regulatory process and may serveto sustain Latin American shellfisheries overtime. The main factors supporting co-managementare: (a) a comparatively reduced scale offishing operations and well-defined boundariesfor the management unit; (b) the allocation ofinstitutionalized co-ownership authority tofishers; (c) the voluntary participation of thefishers in enforcing regulations; (d) theimprovement of scientific information(including data from fishers) to consolidatethe management schemes; (e) the incorporation ofcommunity traditions and idiosyncrasies; and (f)the allocation of territorial use rights forfisheries under a collaborative/voluntarycommunity framework. Chile is identified as anexample in which basic ecological and fisheryconcepts have been institutionalized throughmanagement practices and incorporated into theLaw. Several factors have precludedshellfishery management success in most of theLatin American countries: (a) the social andpolitical instability, (b) the underestimationof the role of fisheries science in managementadvice, (c) the inadequacy of data collectionand information systems, (d) the poorimplementation and enforcement of managementpractices and (e) the uncertainty in short-termeconomic issues.