Diversity,conservation status and threats to native oysters (Ostreidae) around the Atlantic and Caribbean coasts of South America

• 1. Despite the extensive literature on the ecology, systematics and culture of oysters worldwide, an assessment of their diversity, distribution and conservation status for the Atlantic and Caribbean coasts (i.e. depth <50 m) of South America is lacking. Such information is crucial because of the increasing coastal development that threatens most nearshore habitats throughout the region.
• 2. The available information on oysters on Atlantic and Caribbean coasts is reviewed with a focus on identifying regional conservation priorities based on ecological and socio‐economic importance, as well as the magnitude of current or potential threats faced by oyster populations. The current status of α‐ taxonomy within the Ostreidae was also examined.
• 3. Ten species of native Ostreidae (plus three introduced species) inhabit the coastal waters of the Atlantic and Caribbean coasts of South America.
• 4. Oyster species were ranked according to their biological/ecological and socio‐economic value and conservation status within 10 distinct ecoregions. Crassostrea gasar in the Eastern Brazil ecoregion, C. rhizophorae in the Central Caribbean ecoregion and Ostrea puelchana in the North Patagonian Gulfs ecoregion should receive the highest priority for immediate conservation action due to extensive loss of mangrove habitat in the two former regions and evidence of decline of one of the most important populations for the latter. The need for a standardized methodology to assess the status of oyster populations throughout the ecoregions is identified.
• 5. On a local scale, the allocation of territorial use rights for fisheries under a collaborative/voluntary community framework is strongly advocated to fulfil management, conservation and poverty alleviation goals in these developing countries.

Copyright © 2008 John Wiley & Sons, Ltd.     

A comprehensive status,phylogenetic, and anatomical review of Stagnicola caperata (Say, 1829) in the south‐west United States

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Comparison of salinity tolerance and osmoregulation in two closely related species of blennies from different habitats

This study compares osmoregulatory capabilities of two closely related blennies inhabiting different habitats: Salaria pavo which inhabits marine rocky coasts in the Mediterranean and the eastern coasts of the Atlantic Ocean, and Salaria fluviatilis which inhabits freshwater habitats around the Mediterranean, both in rivers connected to the sea and in lakes that for a long time have been separated from the sea. Fishes for this study were collected in Lake Kinneret (Sea of Galilee) (S. fluviatilis) and Habonim beach, Israel, East Mediterranean coast (S. pavo). Both species tolerated salinities of 0, 40 and 100% seawater (0, 14.4 and 36 ppt sea salt respectively). Acclimation for a period of three months to freshwater (S. pavo) and seawater (S. fluviatilis) did not affect survival rates. After acclimation, total body water content of S. fluviatilis remained unaffected by experimental salinities but increased in S. pavo as salinity decreased. The hematocrit of both species increased as salinity increased. Plasma osmolality and Na⁺ concentrations were unaffected by experimental acclimation salinities in S. fluviatilis, but significantly decreased in S. pavo as salinity decreased. The results indicate that S. fluviatilis is able to osmoregulate both in fresh and seawater. S. pavo, living in seawater, while able to tolerate freshwater environment, fails to maintain constant extracellular fluid concentration. It is suggested that S. pavo, or its marine ancestor, has euryhaline capabilities that enabled it to invade freshwater habitats. S. fluviatilis, as the evolutionary result of this invasion, is thus better adapted to freshwater environment, but did not lose its ability to live in seawater.     

A comparison of the population genetics of Lethrinus miniatus and Lutjanus sebae from the east and west coasts of Australia: Evidence for panmixia and isolation

Lethrinus miniatus and Lutjanus sebae are important commercial and recreational species of reef fish. Within Australian waters the former species is less widespread than the latter and has a discontinuous distribution, whilst the latter is continuously distributed in tropical Australian waters. The demographic attributes of these species (e.g. long life span, low rates of natural mortality) make them vulnerable to over-exploitation. Consequently, conservative harvest strategies including no-take zones for these species have been adopted by fisheries management agencies to control exploitation. Information on the genetic stock structure of these species is important for developing specific management strategies. However, little is known about genetic stock structures within and between east and west Australian populations of these species. The current study used the mitochondrial genome hypervariable region 1 (HVR1) of the control region to examine variation between two sites from both the east and west Australian coasts for each species. HVR1 for L. sebae did not differ genetically either within or between coasts (F_st < 0.018, p > 0.15) at the sites studied, suggesting a panmictic population structure. Similarly, L. miniatus did not differ significantly between sites sampled within coast. However, the west coast HVR1 for L. miniatus east and west coast populations, were discrete (F_st of at least 0.92, p < 0.0001). The degree of genetic sub-division between east and west coast populations indicates that they should be managed as discrete stocks. Further, when considering both species, the lower genetic (both haplotype and nucleotide) diversity in three of the four sites on the west coast of Australia, indicates that this region is genetically impoverished and neutrality tests suggest that selection is responsible. Consequently, west Australian populations will be less resilient to perturbations (e.g. fishing, climate change) than east Australian populations, which have higher genetic diversity.     

Migratory connectivity and local site fidelity in red knots on the southern Pacific coast of South America

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Mangrove horseshoe crab (Carcinoscorpius rotundicauda Latreille, 1802) populations reveal genetic break in Strait of Malacca,with connectivity along southern coasts of Peninsular Malaysia

1. The mangrove horseshoe crab, Carcinoscorpius rotundicauda, has divergent populations between the east and west coasts of Peninsular Malaysia, with the southern coast acting as a land barrier. The actual position of such a genetic break along Peninsular Malaysia as well as the connectivity status of the southernmost C. rotundicauda populations with east and west coast populations remain unexplored, however.
2. The aim was to investigate the genetic diversity and structure of C. rotundicauda populations from the west (Kuala Sepetang in State Perak), east (Balok in State Pahang), and southern (Pendas in State Johor) coasts of Peninsular Malaysia. Haemolymph samples from adult C. rotundicauda specimens (n = 152) and eggs from their freshly deposited nests (n = 190) were collected monthly (from January 2016 to January 2017) for the sequencing of mitochondrial cytochrome c oxidase subunit I (COI).
3. Gene isolates of C. rotundicauda from the present study were compared with National Center for Biotechnology Information (NCBI) GenBank sequences to cover most of the range of the species in Asia. A neighbour-joining tree strongly supported two clades, separating the west-coast populations from the south- and east-coast populations, with further substructure patterns.
4. Both haplotype network and barrier analyses revealed a genetic break within the Strait of Malacca instead of the southern tip of Peninsular Malaysia. The southernmost samples from the Strait of Johor formed a haplotypic diverse gene pool that appeared only as a subclade of the eastern populations. In a detailed haplotype network of 347 individuals, individuals with similar COI sequences indicate connectivity between C. rotundicauda on the east and C. rotundicauda on south and south west of Peninsular Malaysia.
5. Overall, the genetic break between C. rotundicauda populations is better explained by the convergent ocean currents and available mangrove habitats on the west coast (i.e. Strait of Malacca), rather than the point of the Malay Peninsula acting as a land barrier alone.

     

Population structure,genetic diversity,and colonization history of the eastern pondmussel,Sagittunio nasutus,in the Great Lakes drainage

1. The eastern pondmussel, Sagittunio nasutus (Bivalvia: Unionida), has declined in abundance and distribution in eastern North America over the last few decades. The declines are predominantly the result of infestation by invasive dreissenid mussels and changes in habitat. The species is now considered imperilled across large portions of its distribution, especially in the Laurentian Great Lakes region.
2. The genetic diversity and structure of the remnant populations in the Great Lakes region were assessed using 10 newly developed microsatellite DNA loci for S. nasutus. Understanding the remaining populations can inform future management projects and determine whether the remnant populations have experienced a genetic bottleneck or a founder effect. We hope that this will inform the conservation of other species in regions founded by, and isolated from, a more genetically diverse source population or with disjointed geographical distributions.
3. Focusing on the Great Lakes region, samples (n = 428) from 62 collection sites in 28 water bodies were collected. Across the locations sampled for S. nasutus 11 genetic populations were identified, with significant genetic differentiation among them. The genetic structure of the species was assessed, with genetic similarities among populations compared and with geographical routes of colonization and gene flow evaluated.
4. Initial colonization from the Atlantic coast into Lake Erie and Lake Ontario is evident, followed by colonization events into nearby inland rivers and lakes. Analyses found evidence of inbreeding in all but one population and evidence of past genetic bottlenecks or strong founder effects in all but four populations. This study deepens our understanding of the genetic past and present of this imperilled species, providing conservation suggestions for the future management of the species.

     

Mechanistic links between climate and fisheries along the east coast of the United States: explaining population outbursts of Atlantic croaker (Micropogonias undulatus)

Climate has been linked to variation in marine fish abundance and distribution, but often the mechanistic processes are unknown. Atlantic croaker (Micropogonias undulatus) is a common species in estuarine and coastal areas of the mid‐Atlantic and southeast coasts of the U.S. Previous studies have identified a correlation between Atlantic croaker abundance and winter temperatures in Chesapeake Bay, and have determined thermal tolerances of juveniles. Here we re‐examine the hypothesis that winter temperature variability controls Atlantic croaker population dynamics. Abundance indices were analyzed at four life history stages from three regions along the east coast of the U.S. Correlations suggest that year‐class strength is decoupled from larval supply and is determined by temperature‐linked, overwinter survival of juveniles. Using a relation between air and water temperatures, estuarine water temperature was estimated from 1930 to 2002. Periods of high adult catch corresponded with warm winter water temperatures. Prior studies indicate that winter temperature along the east coast is related to the North Atlantic Oscillation (NAO); variability in catch is also correlated with the NAO, thereby demonstrating a link between Atlantic croaker dynamics, thermal limited overwinter survival, and the larger climate system of the North Atlantic. We hypothesize that the environment drives the large‐scale variability in Atlantic croaker abundance and distribution, but fishing and habitat loss decrease the resiliency of the population to periods of poor environmental conditions and subsequent weak year classes.     

The potential of Arctic charr, Salvelinus alpinus (L.), for mariculture

There would appear to be considerable potential for Arctic charr, Salvelinus alpinus (L.), to be cultured in marine conditions in countries where coastal winter salinity is below oceanic, and temperatures remain above freezing. Sea lochs on the west coast of Scotland represent one such environment where freshwater run-off leads to depressed salinities (20-30 practical salinity units) and the North Atlantic Drift leads to winter sea water temperatures typically around 6-8^oC.     

Historical DNA as a tool to genetically characterize the Mediterranean sand tiger shark (Carcharias taurus,Lamniformes: Odontaspididae): A species probably disappeared from this basin

1. The sand tiger shark (Carcharias taurus) is a coastal species distributed in temperate and sub‐tropical waters, classified as ‘Vulnerable’ at global level and ‘Critically endangered’ in eastern Australia, south‐western Atlantic Ocean, and Mediterranean Sea. Six populations (north‐western Atlantic, Brazil, South Africa, Japan, eastern Australia, and western Australia) with low genetic diversity and limited gene flow were identified worldwide, but genetic information for many other geographic areas are still missing. Specifically, this species is listed in several reports as part of the Mediterranean fauna, even if there has been a lack of catches and sightings in recent years in this basin. To clarify the origin of C. taurus individuals caught in the past in the Mediterranean Sea, historical samples were genetically analysed.
2. Nine samples with certain Mediterranean origin were collected from different European museums. DNA was extracted and ~600 bp of the mitochondrial DNA control region were amplified using eight overlapping species‐specific primer pairs. Sequences obtained were aligned with all the haplotypes globally known so far.
3. Genetic analysis revealed the misidentification of one museum specimen. Among the remaining Mediterranean historical samples, three different haplotypes were recovered. Two of them previously observed only in South Africa and one described in both South African and Brazilian populations.
4. Results suggest a genetic relationship between Mediterranean sand tiger sharks and those from the western Indian Ocean. According to previous studies, we hypothesized that, during the Pleistocene, the cold Benguela upwelling barrier was temporarily reduced allowing the passage of C. taurus individuals from the Indian to Atlantic Ocean. After the restoration of this phylogeographic barrier some individuals were trapped in the Atlantic Ocean and probably migrated northward colonizing the western African coasts and the Mediterranean Sea.

     

Atlantic coast feeding habits of striped bass: a synthesis supporting a coast-wide understanding of trophic biology

The recent increase in the Atlantic coast population of striped bass, Morone saxatilis (Walbaum), prompted managers to re‐evaluate their predatory impact. Published and unpublished diet data for striped bass on the Atlantic Coast of North America were examined for geographical, ontogenetic and seasonal patterns in the diet and to assess diet for this species. Diets of young‐of‐the‐year (YOY) striped bass were similar across the Upper Atlantic (UPATL), Chesapeake and Delaware Bays (CBDEL) and North Carolina (NCARO) areas of the Atlantic coast where either fish or mysid shrimp dominate the diet. For age one and older striped bass, cluster analysis partitioned diets based on predominance of either Atlantic menhaden, Brevoortia tyrannus (Latrobe), characteristic of striped bass from the CBDEL and NCARO regions, or non‐menhaden fishes or invertebrates, characteristic of fish from the UPATL, in the diet. The predominance of invertebrates in the diets of striped bass in the UPATL region can be attributed to the absence of several important species groups in Northern waters, particularly sciaenid fishes, and to the sporadic occurrences of Atlantic menhaden to UPATL waters. In all regions, across most seasons and in most size classes of striped bass, the clupeiod fishes; menhaden, anchovies (Anchoa spp.) and river herrings (Alosa spp,) and Atlantic herring, Clupea harengus L., dominated the diets of striped bass above the first year of life.     

Genetic structure of the exotic hard clam <Emphasis Type="Italic">Mercenaria mercenaria</Emphasis> in Tokyo Bay,determined using mitochondrial DNA

The hard clam Mercenaria mercenaria was unintentionally introduced into Tokyo Bay during the 1990s. We analysed 528 bp of partial mitochondrial DNA of the cytochrome c oxidase subunit 1 (COI) gene extracted from 135 specimens collected from populations at five sites in Tokyo Bay to determine the genetic structure of this species. Mercenaria mercenaria populations in Tokyo Bay were dominated by haplotype 1, as in the native area. Haplotype 3, which is absent in the populations north of Cape Hatteras (North Carolina, USA) was detected at all five sites. The haplotype diversity in Tokyo Bay was as high as that in the native area, except at two canal sites, while the nucleotide diversity was lower. Thirty-five new haplotypes were found that displayed only a few nucleotide differences. Pairwise F _ST values were not significantly different between any sites in the Tokyo Bay and the east coast of America, with values for all sites in Tokyo Bay clustering near the Florida populations. The analysis of molecular variance (AMOVA) results also support this result. This study revealed that M. mercenaria populations in Tokyo Bay have a high haplotype diversity and that populations around Florida may be the source region.     

Meta‐analysis of growth rates for a circumpolar fish,the northern pike ( Esox lucius), with emphasis on effects of continent,climate and latitude

For circumpolar species, little is known on how somatic growth rates can vary at large, transcontinental spatial scales. In this study, a meta‐analysis of growth rates was conducted for northern pike ( Esox lucius) across North America and Eurasia. Growth rates of northern pike did not differ between North American and ‘coastal Eurasian’ pike (e.g., UK, Ireland, Sweden), while growth rates for both of these groups were significantly higher compared to ‘inland Eurasian’ pike (mainly in Russia). There was no difference in growth between lentic and lotic habitats on either continent. In North America, pike growth was positively correlated with temperature, but in Eurasia, pike growth correlated poorly with most climatic variables. Similarly, maximum longevity in pike populations was significantly predicted by latitude in North America, but not in Eurasia. After standardising annual pike growth by the thermal opportunity for growth, a highly significant countergradient growth relationship was found for North American pike, while a significant, but considerably less predictive countergradient growth relationship was found for Eurasian pike. This study provides novel insights into the ecology of a circumpolar species and how populations function at extraordinarily large spatial scales. First, pike appear to be cosmopolitan across hydrologic habitats having fast or slow growth in either lentic or lotic environments. Secondly, continental‐scale differences in pike growth rates are suggestive of major genetic and life‐history differences. Finally, variable climate–growth relationships and countergradient growth patterns indicate that global climate change is likely to affect circumpolar fishes like pike in complex, nonlinear ways.     

Short range dispersal by a rare,obligate freshwater crustacean Triops cancriformis (Bosc)

1. that there are populations of this species that, because of their unusual life history, remain undetected.
2. that this species is able to disperse over distances of several kilometres.

Incubation of sediment samples demonstrated the presence of T. cancriformis at two previously unknown sites. One further serendipitous discovery of adults at another site is also reported, bringing to eight the number of discrete ponds where this species has been recorded on the north Solway coast since 1907.

Only five natural populations are probably extant in the UK (with a sixth introduced population still extant). Four of these are on the Solway coast suggesting that this area is a conservation hotspot.

The inference from the spatial and temporal pattern of records of T. cancriformis from the Solway coast is that this species is able to disperse between discrete habitat patches over distances of at least several kilometres and successfully colonize new sites.

The mechanisms of this dispersal are unknown but transfer of material during floods or on the feet of deer, livestock, humans, waterfowl, or on farm machinery are all highly possible.

Copyright © 2013 John Wiley & Sons, Ltd.     

Global spread and evolution of viral haemorrhagic septicaemia virus

Viral haemorrhagic septicaemia virus (VHSV) is a rhabdovirus that infects over 48 species of teleosts and is lethal in many. VHSV threatens marine and aquatic fisheries. VHSV was first discovered outside Europe in 1988 in fish from the Pacific coast of North America. In 1994, VHSV was discovered in Newfoundland. In 2003, VHSV was isolated from fish in Lake St. Clair (Michigan and Ontario). In this study, we used 46 nucleotide sequences for the glycoprotein gene from 12 studies and 150 nucleotide sequences for the nucleoprotein gene from nine studies. We combined phylogenetics and a geographic information system to visualize the transmission paths of VHSV lineages. We also reconstructed the spread of VHSV lineages through optimization of geographic data for viral isolates on phylogenetic trees. We demonstrate that VHSV was transmitted from the North Atlantic Ocean and/or Baltic Sea to the Atlantic coast of North America and Japan in independent events. From the Atlantic coast, the virus was transmitted independently to the Laurentian Great Lakes and the Pacific coast of Canada and the contiguous United States. From the Pacific Northwest, the virus was transmitted to Asia and Alaska in independent events. These results clarify the debate ongoing in the literature on the geographic spread of VHSV.     

Factors affecting habitat selection by a small spawning charr population, bull trout, Salvelinus confluentus: implications for recovery of an endangered species

Bull trout, Salvelinus confluentus (Suckley), populations are declining in many streams of North America and are listed under the Endangered Species Act in the United States. Many small populations are isolated in fragmented habitats where spawning conditions and success are not well understood. Factors affecting habitats selected for redds by spawning bull trout and redd habitat characteristics within Gold Creek, a headwater stream in the Yakima River within the Columbia River basin, Washington State, USA, were evaluated. Most spawning (>80% of the redds) occurred in upstream habitats after dewatering of downstream channels isolated fish. Habitats were selected or avoided in proportions different to their availability. For example, most bull trout selected pools and glides and avoided riffles despite the latter being more readily available. Although preferences suggest influences of prolonged fish entrapment, site fidelity could be important. A habitat with redds commonly contained abundant cover, gravel substratum and higher stream flows. The major factors influencing habitat selection by spawning fish and their persistence in streams of the Yakima and Columbia River regions include entrapment of fish by dewatering of channels and geographical isolation by dams. The goal of the US Government's recovery plan is ‘to ensure the long‐term persistence of self‐sustaining bull trout populations’. Recovery plans linked to provisions for protecting and conserving bull trout populations and their habitats were recommended. Landscape approaches are needed that provide networks of refuge habitats and greater connectivity between populations. Concurrent recovery efforts are encouraged to focus on protecting small populations and minimizing dangers of hybridization.     

Habitat associations of the Threatened pugnose minnow (Opsopoeodus emiliae) at the northern edge of the species range

Pugnose minnow (Opsopoeodus emiliae) is a small, reclusive species that is widespread in North America, but is one of the rarest fishes in Canada, found in less than 12 known localities in southwestern Ontario. In contrast to most pugnose minnow populations across the global range, Canadian populations are primarily found in turbid systems, potentially indicating persistence in suboptimal conditions. We used data from a multi-gear species and habitat survey in the Canard River, Ontario, a system dominated by agricultural inputs and the best-known capture site of the species in Canada, to parameterise multi-gear occupancy models for understanding the relationship between pugnose minnow occupancy and microhabitat features, including the role of turbidity. Almost 300 pugnose minnow were captured, representing the largest single collection of the species in Canadian history. The best occupancy model indicated that the probability of pugnose minnow occupancy was highest in the deepest sites with the lowest water clarity (i.e. high turbidity); however, competing models suggested that occupancy was highest at sites with wild celery (Vallisneria americana) and higher water clarity, signifying that habitats with low turbidity may be utilised if sufficient physical cover exists. Together, our results suggest that Canadian pugnose minnow populations occupy and potentially favour turbid conditions, possibly to avoid visual predators in clearer habitats. It remains uncertain whether this abiotic association represents a long-term, viable, local adaptation or whether persistence of pugnose minnow in the Canard River is at risk unless significant water quality improvements can be made.     

Insights into population genetics,connectivity and demographic history of the longnosed skate Dipturus oxyrinchus (Linnaeus, 1758) in the western Mediterranean Sea

1. Genetic information is crucial for the conservation of Dipturus oxyrinchus (Linnaeus, 1758), a threatened large skate with declining populations over most of its geographical range. The main aim of the present study was to investigate the genetic structure, connectivity and demographic history of the longnosed skate in Sardinia (western Mediterranean Sea).
2. Patterns of population structure were assessed in 175 specimens from six sampling sites. Variation in two mitochondrial genes (cytochrome c oxidase subunit I (COI) and control region) highlighted high genetic diversity and low but significant genetic differentiation among sites, which clustered into three groups corresponding to the north‐west, north‐east and south Sardinian coasts.
3. The observed genetic structuring could presumably depend on a combination of past geological events, contemporary restrictions to dispersal and biological characteristics of the species (e.g. site‐fidelity, no pelagic larval stage, limited dispersal of juveniles and/or adults).
4. Demographic analyses showed signs of past population expansion, but substantial current stability of Sardinian populations. From a conservation perspective, these results are encouraging, and indicate that Sardinian populations are still large and stable, and seem not to have suffered negative side‐effects from the ever‐growing fishing pressure in the region.
5. The occurrence of genetic structuring strongly supported the close monitoring of populations to identify any erosion of their gene pool, and high genetic variability of the Sardinian D. oxyrinchus populations could thus represent priority populations for conservation purposes, providing potential sources for recolonization in cases of local extinctions in other areas of the distribution range of the species.
6. When the sequences from Sardinia were compared with those available from other areas, the data seem to exclude the possibility that the Atlantic and Mediterranean host totally isolated populations or even different species, as recently suggested. However, additional markers and a larger sampling sites are needed to confirm these findings.

     

Salinity tolerance of non‐native suckermouth armoured catfish (Loricariidae: Pterygoplichthys) in south‐eastern Mexico: implications for invasion and dispersal

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Tracking shifts in Atlantic mackerel (Scomber scombrus) larval habitat suitability on the Northeast U.S. Continental Shelf

Climate change has altered the oceanographic environment and subsequently the habitats of marine species. Fish and invertebrate populations’ responses to habitat include movement with latitude and depth to remain within their fundamental niches. The northwest Atlantic mackerel (Scomber scombrus) population has fluctuated over the last century due in part to changes in the environment. We used species distribution models to understand the influence of the physical (temperature) and biological (zooplankton) environment on mackerel larval abundance, and how such relations have determined larval habitat suitability in the Northeast U.S. Shelf. Atlantic mackerel larval presence and abundance correlated with sea temperature and copepod abundances, suggesting that larval survival may be sensitive to specific temperatures and zooplankton prey. Predicted abundances were spatially interpolated to estimate Atlantic mackerel larval suitable habitat. Metrics for habitat quality indicate that the Mid‐Atlantic Bight has become less suitable over time. Since the 1970s, the proportion of Northeast U.S. Shelf suitable habitat located in the Mid‐Atlantic Bight has decreased, as southern New England and the western Gulf of Maine regions have become more suitable. Habitat suitability within the Northeast U.S. Shelf has shifted northeast: from the Mid‐Atlantic Bight‐southern New England border towards the northeast portion of southern New England. While total Northeast U.S. Shelf habitat suitability has decreased since the 1970s, the decline in the time series trend was not statistically significant. Thus, while select ecoregions have decreased in habitat suitability, larval habitat does not appear to be the only contributor to decreases in the U.S. Atlantic mackerel contingent.