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The yellow clam fishery in Uruguay provides a longstanding case study of co-management in small-scale fisheries. This paper employs a participatory approach to examine the co-management experience in the yellow clam fishery and distil numerous lessons for implementing the Voluntary Guidelines for Securing Sustainable Small-Scale Fisheries in the Context of Food Security and Poverty Eradication (SSF Guidelines). There were three main findings in the study. First, from the perspective of the fishers, co-management has proven successful in advancing gender equity, human rights and subjective well-being within the fishery, which align with the SSF Guidelines. Second, co-management is likely most effective at achieving the goals of the SSF Guidelines when it is accompanied by wide-scale structural changes in legislation and efforts to improve its coherence across areas of jurisdiction. Third, the nature and rate of socio-economic and ecological change currently being experienced - and which is expected to continue - requires a significant amount of flexibility in co-management arrangements in order for them to deliver on the intended outcomes of the SSF Guidelines. These findings help further the implementation of the SSF Guidelines through co-management in the yellow clam fishery, and serve as a learning platform for scaling up good practices to other small-scale fisheries of Uruguay. Additionally, the findings can also be applied in other regions dealing with similar issues in the management and governance of small-scale fisheries. [ABSTRACT FROM AUTHOR]

The Ecosystem Approach to Fisheries (EAF) has been proposed as a holistic approach for managing fisheries. Although EAF is a widely accepted concept, many challenges remain in its practical implementation, particularly in small-scale fisheries (SSFs) in developing countries. Long-term evaluations of EAF performance in SSFs are scarce and even fewer when considering co-management (Co-M) as the institutionalized governance mode implemented under an EAF scheme (EAF/Co-M). This paper addresses the implementation, development process and performance of an EAF/Co-M in the yellow clam SSF of Uruguay through multiple fishery indicators for the period 2007–2015. EAF/Co-M showed a highly positive response in abundance and biomass of the harvestable stock through time, stabilization in individual sizes above the minimum landing size limit, and a fairly constant exploitation rate at low levels that did not exceed 25%, accompanied by relatively constant CPUE values through time. Temporal variations in unit price and revenues per unit of effort showed higher values after EAF/Co-M implementation. These indicators, taken together, suggest that the enhanced production capacity of the fishery during the EAF/Co-M implementation did not have a negative impact on the stock. The number of fishers involved in the activity has not changed markedly through time, but two remarkable positive changes occurred in the composition of the group: (i) an increasing number of licenses allocated twice in a row through time, which suggests the consolidation of a stable group of fishers; and (ii) a significant increase in the number of women directly involved in the fishing activity. This study provides solid empirical evidences to the idea that EAF, coupled with Co-M as a formal governance mode, could be helpful to address management tasks and to improve social–ecological conditions of SSFs. [ABSTRACT FROM AUTHOR]

Microscopic analysis and field sampling procedures were used to compare demographic and reproductive strategies of the intertidal wedge clam Donax hanleyanus (Bivalvia: Donacidae) in two exposed sandy beaches with contrasting morphodynamics (reflective vs. dissipative) during 13 consecutive months. Histological analysis showed that: (1) the reproductive cycle of D. hanleyanus was more extended in the dissipative beach, and this was true for all the three pre-active (beginning of gonadal activity), active (maturation) and spawning stages; and (2) males and females showed significantly smaller sizes at sexual maturity at the reflective beach. Even though successive increments in proportion and mature at size were observed, the sigmoid function was significantly steeper at the reflective Arachania for both sexes, suggesting an abrupt transition to maturity. Field sampling revealed a more extended recruitment period at the dissipative beach, where recruits were also significantly more abundant than at the reflective beach. These results give support for the habitat harshness hypothesis, which predicts that in intertidal species capable of sustaining populations across a wide spectrum of physical conditions, such as D. hanleyanus, abundance, recruitment, size at maturity and extent of reproductive and recruitment seasons increase from reflective to dissipative beaches. However, a recent hypothesis suggests that reflective beaches acting as sink populations were not sustained, because mature and spawning individuals of both sexes were found in the reflective beach throughout the study period. Thus, we suggest that post-settlement processes are critical in modulating population patterns for this bivalve. [ABSTRACT FROM AUTHOR]

Demographic and life-history attributes of the yellow clam, Mesodesma mactroides, were analyzed along exposed sandy beaches of the Atlantic coast of South America, from Brazil (32°S) to Argentina (41°S), covering most of its geographical range (24-41°S). Population features varied markedly within this range and exhibited systematic geographical pat- terns of variation. Abundance and growth/mortality rates significantly decreased from northern (Brazil and Uruguay) to southern (Argentina) populations. Snapshot information at the edge of its northern geographical range suggests a large-scale unimodal distribution pattern. Northern populations also had an extended or quasi-continuous recruitment season, whereas Argentinean populations had seasonal recruitment that became negligible at the southernmost edge of the range (41°S). Maximum individual sizes increased nonlinearly with latitude. This result, when considered together with density patterns, provided the second large-scale evidence of scaling of population density to body size in a sandy-beach population. Lifespan increased with latitude, ranging between 3 and >7 years. Length frequency- distribution analysis revealed marked intra-annual growth patterns for two populations located 7° latitude apart. Variations in water temperature explained large-scale differences in the demography and population dynamics of the yellow clam, and the high plasticity over latitudinal gradients leads to an adjustment of the phenotype-environment relationship. Long-term studies in Uruguayan beaches suggest that wide population fluctuations are the result of intertwined forces of environmental, density-dependent, and human-induced factors operating together at different spatiotemporal scales. As this species with planktonic larvae is structured as a metapopulation, future studies should incorporate a number of hierarchical scales to better understand macroscale variations in demographic patterns and life-history traits. [ABSTRACT FROM AUTHOR]

We studied some aspects of the population dynamics of the yellow clam Mesodesma mactroides (Deshayes, 1854) which inhabits the eastern sandy beaches of Uruguay. Observations were made from March 1983 through March 1985 (harvesting season), and additional data from January 1988 to December 1989 (closed season) were also included in the analyses. Parameters of growth and mortality were estimated by methods that make use of age or length information. An age/length relationship was constructed by counting growth rings. Results were consistent with those obtained with modal class progression analysis and other length/frequency methods. The growth curve obtained from the age/length relationship did not account for seasonality in growth rate, and a seasonal growth model explained growth oscillations in a better way. The instantaneous coefficient of natural mortality ( M) estimated for the closed season was 1.64, whereas an increase in fishing mortality ( F) was observed during 1984. Age composition did not change during the 2 yr of study, and the first 6 mm class accounted for over 50% of the population. The main contribution of recruits was observed between late summer and early fall (February to April), and the recruitment pattern suggested one main settlement period per year. Growth and recruitment success appeared to be regulated by density-dependence processes. Some implications for management are considered in this context. Methodological aspects concerning the reliability of empirical equations and programs for estimating growth and mortality are discussed. [ABSTRACT FROM AUTHOR]