967 resultados para Oyster fisheries
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Globally, small-scale fisheries (SSFs) are driven by climate, governance, and market factors of social-ecological change, presenting both challenges and opportunities. The ability of small-scale fishermen and buyers to adapt to changing conditions allows participants to survive economic or environmental disturbances and to benefit from optimal conditions. This study presented here identifies key large-scale factors that drive SSFs in California to shift focus among targets and that dictate long-term trends in landings. We use Elinor Ostrom’s Social-Ecological System (SES) framework to apply an interdisciplinary approach when identifying potential factors and when understanding the complex dynamics of these fisheries. We analyzed the interactions among Monterey Bay SSFs over the past four decades since the passage of the Magnuson Stevens Fisheries Conservation and Management Act of 1976. In this region, the Pacific sardine (Sardinops sagax), northern anchovy (Engraulis mordax), and market squid (Loligo opalescens) fisheries comprise a tightly linked system where shifting focus among fisheries is a key element to adaptive capacity and reduced social and ecological vulnerability. Using a cluster analysis of landings, we identified four modes from 1974 to 2012 that were dominated by squid, sardine, anchovy, or lacked any dominance, enabling us to identify external drivers attributed to a change in fishery dominance during seven distinct transition points. Overall, we show that market and climate factors drive the transitions among dominance modes. Governance phases most dictated long-term trends in landings and are best viewed as a response to changes in perceived biomass and thus a proxy for biomass. Our findings suggest that globally, small-scale fishery managers should consider enabling shifts in effort among fisheries and retaining existing flexibility, as adaptive capacity is a critical determinant for social and ecological resilience.
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The present study describes the biofouling composition of the surface of the mangrove oyster Crassostrea rhizophorae (Guilding, 1828), cultivated in an Amazon estuary, located in the state of Pará, northern Brazil. In total, 6.124 macroinvertebrates were sampled in the months of July, August, October and December 2013. Collected epifauna was presented by five taxa (Bivalvia, Gastropoda, Polychaeta, Crustacea and Anthozoa), 20 families and 37 species. Bivalvia was the most abundant class, presenting 5.183 mussels Mytella charruana (d'Orbigny, 1842). Knowledge of biofouling composition associated to the surface cultured bivalves enables the implementation of mitigation measures to the impacts caused by this association.
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Ocean acidification, due to anthropogenic CO2 absorption by the ocean, may have profound impacts on marine biota. Calcareous organisms are expected to be particularly sensitive due to the decreasing availability of carbonate ions driven by decreasing pH levels. Recently, some studies focused on the early life stages of mollusks that are supposedly more sensitive to environmental disturbances than adult stages. Although these studies have shown decreased growth rates and increased proportions of abnormal development under low pH conditions, they did not allow attribution to pH induced changes in physiology or changes due to a decrease in aragonite saturation state. This study aims to assess the impact of several carbonate-system perturbations on the growth of Pacific oyster (Crassostrea gigas) larvae during the first 3 days of development (until shelled D-veliger larvae). Seawater with five different chemistries was obtained by separately manipulating pH, total alkalinity and aragonite saturation state (calcium addition). Results showed that the developmental success and growth rates were not directly affected by changes in pH or aragonite saturation state but were highly correlated with the availability of carbonate ions. In contrast to previous studies, both developmental success into viable D-shaped larvae and growth rates were not significantly altered as long as carbonate ion concentrations were above aragonite saturation levels, but they strongly decreased below saturation levels. These results suggest that the mechanisms used by these organisms to regulate calcification rates are not efficient enough to compensate for the low availability of carbonate ions under corrosive conditions.
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The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.
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The malacocultura, particularly oyster farming, appears on the world stage as one of the most viable alternatives to fishing decline and supply of fresh product. In Brazil, the development of mollusc cultivationis through the genus oyster cultivation Crassostrea, among them Crassostrea rhizophorae (Guilding, 1828), known for oyster-the-swamp, one of the main species of farmed bivalves in the state of Pará. This so it aimed to characterize the biomorphometrics relations, estimate the Shape Stabilization Index (IEF) of the shell and the yield of edible meat C. rhizophorae grown in an Amazonian coast, state of Pará, northern Brazil. When all is sampled 1,028 individuals, in April 2016, measuring the external morphometric measures (length, width and height) and total and visceral biomass. The results obtained are C. rhizophorae with (1) excellent biomorphometrics relationships among both external measures, the measures of the shell and biomass generating equations that satisfy morphometric pet species, (2) yield of edible meat 15% of the total biomass and variation in the shell along its development to adulthood, with a tendency to stabilize the reach 60mm in length.
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Exclusive Fishing Zones (EFZs) are a type of place-based management tool often used to mitigate conflicts between fishing sectors by granting fishing rights to one of the sectors. This case study enhances our knowledge of the pre- and post-implementation processes associated with EFZs as well as its consequences for fish stocks and artisanal fishers and their families. The study draws upon interviews with artisanal fishers and key informants related to an EFZ established in 2008 in Colombia (the Chocó-EFZ). The findings of this research indicate that conflicts at sea and on land between artisanal and industrial fisheries triggered the Chocó-EFZ process. Results also show some potential benefits of the Chocó-EFZ including: a) mitigating conflicts between artisanal fishers and industrial shrimpers; b) contributing to the food security of artisanal fishing households and sustaining local fish stocks; c) supporting an existing informal community-based management as well as promoting the development of a co-management regime. Potential negative effects of the Chocó-EFZ include: a) displacement of industrial fishing effort and, b) job loss within the industrial shrimp industry. The findings of this research also indicate that there are multiple factors that jeopardize the effectiveness and continuation of the Chocó-EFZ, some of which include diversity of fisheries, power struggles among stakeholders, and disagreement about exclusive access to fish resources.
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This study explores the giant oyster Hyotissa hyotis as a novel environmental archive in tropical reef environments of the Indo-Pacific. The species is a typical accessory component in coral reefs, can reach sizes of tens of centimetres, and dates back to the Late Pleistocene. Here, a 70.2-mm-long oxygen and carbon isotope transect through the shell of a specimen collected at Safaga Bay, northern Red Sea, in May 1996, is presented. The transect runs perpendicularly to the foliate and vesicular layers of the inner ostracum near the ligament area of the oyster. The measured d18O and d13C records show sinusoidal fluctuations, which are independent of shell microstructure. The d13C fluctuations exhibit the same wavelength as the d18O fluctuations but are phase shifted. The d18O record reflects the sea surface temperature variations from 1957 until 1996, possibly additionally influenced by the local evaporation. Due to locally enhanced evaporation in the semi-enclosed Safaga Bay, the d18Oseawater value is estimated at 2.17 per mil, i.e., 0.3-0.8 per mil higher than published open surface water d18O values (1.36-1.85 per mil) from the region. The mean water temperature deviates by only 0.4°C from the expected value, and the minimum and maximum values are 0.5°C lower and 2.9°C higher, respectively. When comparing the mean monthly values, however, the sea surface temperature discrepancy between reconstructed and global grid datasets is always <1.0°C. The d13C signal is weakly negatively correlated with regional chlorophyll a concentration and with the sunshine duration, which may reflect changes in the bivalve's respiration. The study emphasises the palaeogeographic context in isotope studies based on fossils, because coastal embayments might not reflect open-water oceanographic conditions.
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The authors wish to acknowledge the valuable comments and suggestions made by members of the Committee of Fisheries of the European Parliament. The authors also thank the financial support of the European Parliament (IP/B/PECH/IC/2014–084) and the assistance of Ojama Priit and Marcus Brewer. SV acknowledges the financial support from the Spanish Agency for International Development Cooperation (AECID) (Grant no 11-CAP2–1406) and the Galician Government (Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia) (Grant no R2014/023). MC acknowledges the financial support from the European Commission through the Marie Curie Career Integration Grant Fellowships – PCIG10-GA-2011–303534 - to the BIOWEB project. CP and GP acknowledge the financial support of Caixa Geral de Depósitos (Portugal) and the University of Aveiro. CP would also like to acknowledge FCT/MEC national funds and FEDER co-funding, within the PT2020 partnership Agreement and Compete 2020, for the financial support to CESAM (Grant no UID/AMB/50017/2013). JMDR and JGC thanks the financial support from the European Commission (MINOW H2020-SFS-2014–2, No 634495) and Xunta de Galicia (GRC 2015/014 and ECOBAS). MA acknowledges financial aid of Xunta de Galicia through Project GPC 2013–045. URS and CP acknowledge the Too Big to Ignore Partnership supported by the Social Sciences and Humanities Research Council of Canada (SSHRC).