Mixed stock origin of Atlantic bluefin tuna in the U.S. rod and reel fishery (Gulf of Maine) and implications for fisheries management

Kerr, Lisa A.; Whitener, Zachary T.; Cadrin, Steven X.; Morse, Molly R.; Secor, David H.; Golet, Walter J.

doi:10.1016/j.fishres.2019.105461

Cited by 17 publications

(23 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This baseline was then used to predict contingent membership (northern or southern) of age ≥ 2 unknown adult samples collected within the US shelf waters. For adult classification, a threshold classification probability level of > 0.7 was employed for probability of assignment to each contingent to account for the lack of strong separation between the two contingents in the baseline stable isotope composition 50 . Adult samples that fell below this threshold probability were unassigned to either contingent and were excluded from further analyses.…”

Section: Methodsmentioning

confidence: 99%

Multi-decadal trends in contingent mixing of Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic from otolith stable isotopes

Arai

Castonguay

Secor

2021

Sci Rep

Self Cite

View full text Add to dashboard Cite

The Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic is comprised of northern and southern components that have distinct spawning sites off Canada (northern contingent) and the US (southern contingent), and seasonally overlap in US fished regions. Thus, assessment and management of this population can be sensitive to levels of mixing between contingents, which remain unknown. Multi-decadal trends in contingent mixing levels within the US fisheries region were assessed, and the contingent composition across seasons, locations, ages, and size classes were characterized using archived otoliths and developing a classification baseline based on juvenile otolith carbon and oxygen stable isotopes (δ13C/δ18O values). Classification of age ≥ 2 adults demonstrated that northern contingent mixing was prevalent within the US continental shelf waters during the past 2 decades (2000–2019), providing an important seasonal subsidy to the US winter fishery despite substantial depletion in spawning stock biomass of the dominant northern contingent. While the majority of older fish were of the northern contingent during the early 2000s, the southern contingent contribution increased with age/size class during the recent period (2013–2019). Spatial mixing was most prevalent during February and March when the northern contingent occurred as far south as the Delmarva Peninsula, but were mostly absent from US waters in May. A positive relationship (albeit not significant; r = 0.60, p = 0.07) occurred between northern contingent mixing and US fisheries landings, which could imply that higher contingent mixing levels might be associated with greater landings for the US winter mackerel fishery. The yield of the Northwest Atlantic mackerel depends upon the status of the northern contingent, with the southern contingent possibly more prone to depletion. Spatially explicit stock assessment models are recommended to conserve both productivity and stability in this two-component population.

show abstract

Section: Methodsmentioning

confidence: 99%

Multi-decadal trends in contingent mixing of Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic from otolith stable isotopes

Arai

Castonguay

Secor

2021

Sci Rep

Self Cite

View full text Add to dashboard Cite

show abstract

“…Due to its smaller size relative to the eastern stock of ABFT, the western stock is particularly vulnerable to over-exploitation within mixing areas. Similarly, error and uncertainty in estimates of stock composition has a particularly strong influence on the assessment of western ABFT 78 . The integrated method of stock discrimination offers a highly accurate tool for discriminating between ABFT of western and eastern origin that resolves some disagreement between genetic and stable isotope based assignments and can provide reliable estimates of stock composition.…”

Section: Area Number Locationmentioning

confidence: 99%

Combining genetic markers with stable isotopes in otoliths reveals complexity in the stock structure of Atlantic bluefin tuna (Thunnus thynnus)

Brophy

Rodríguez-Ezpeleta

Fraile

et al. 2020

Sci Rep

View full text Add to dashboard Cite

Atlantic bluefin tuna (Thunnus thynnus) from the two main spawning populations in the Mediterranean and Gulf of Mexico occur together in the western, central and eastern Atlantic. Stock composition of catches from mixing areas is uncertain, presenting a major challenge to the sustainable management of the fisheries. This study combines genetic and chemical markers to develop an integrated method of population assignment. Stable isotope signatures (δ13C and δ18O) in the otolith core of adults from the two main spawning populations (adult baselines) showed less overlap than those of yearlings (12–18 months old) from western and eastern nursery areas suggesting that some exchange occurs towards the end of the yearling phase. The integrated model combined δ18O with four genetic markers (SNPs) to distinguish the adult baselines with greater accuracy than chemical or genetic markers alone. When used to assign individuals from the mixing areas to their population of origin, the integrated model resolved some (but not all) discrepancies between the chemistry and genetic methods. Some individuals in the mixing area had otolith δ18O values and genetic profiles which when taken together, were not representative of either population. These fish may originate from another Atlantic spawning area or may represent population contingents that move away from the main spawning areas during the first year of life. This complexity in stock structure is not captured by the current two-stock model.

show abstract

“…Posterior probability values were averaged across iterations, and confidence intervals were inspected for consistency in assignment. An average assignment probability threshold of 70%, to either one of the reference populations was selected based on previous studies (Puncher et al 2018;Kerr et al 2020). We have used a lower threshold (70%) to adjust for lower levels of genetic differentiation commonly found among broadcast spawners and highly migratory marine species, relative to anadromous and freshwater fishes.…”

Section: Methodsmentioning

confidence: 99%

“…For example, studies using the composition of stable isotope contained in otoliths and the concentration of organochlorines in body tissues have estimated that a high proportion (24-83%) of ABFT caught along the Atlantic coast of the USA (mid-Atlantic Bight) are of Mediterranean origin (Rooker et al 2008a,b;Dickhut et al 2009;Graves et al 2015;Kerr et al 2020). A recent genetic study determined that the proportion of Mediterranean origin ABFT in Western fishing areas varied between 23-56% (average of 37%) (Rodríguez-Ezpeleta et al 2019).…”

Section: Proportions Of Assigned Individualsmentioning

confidence: 99%

Individual assignment of Atlantic bluefin tuna in the northwestern Atlantic Ocean using single nucleotide polymorphisms reveals an increasing proportion of migrants from the eastern Atlantic Ocean

Puncher

Hanke

Busawon

et al. 2022

Can. J. Fish. Aquat. Sci.

View full text Add to dashboard Cite

Identifying the origin of fish contained in a mixed fishery is critical for accurate stock assessments and the subsequent development of appropriate management strategies. Using a panel of 92 SNPs developed to differentiate Atlantic bluefin tuna (Thunnus thynnus) from the two main spawning areas (Gulf of Mexico and Mediterranean Sea), we used individual assignment to determine composition of feeding aggregations in the northwestern Atlantic Ocean (Gulf of Maine, Bay of Fundy, Scotian Shelf, Gulf of St. Lawrence, coastal Newfoundland). Among the 3,163 individuals collected between 2004 and 2018, we found that among lower age groups (<15 years) the spawning stock providing the most recruits to the Canadian fishery transitioned from Western Atlantic to Mediterranean origin over time. While the majority of older adults (>15 years) have consistently been of Western Atlantic origin, the disparity in the proportional contribution of western and eastern spawning groups narrowed significantly over the 14-year study period. Our results can be used to inform population-specific exploitation rates, improve stock assessments, identify age-dependent habitat use and areas suitable for additional conservation efforts.

show abstract

Mixed stock origin of Atlantic bluefin tuna in the U.S. rod and reel fishery (Gulf of Maine) and implications for fisheries management

Cited by 17 publications

References 26 publications

Multi-decadal trends in contingent mixing of Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic from otolith stable isotopes

Multi-decadal trends in contingent mixing of Atlantic mackerel (Scomber scombrus) in the Northwest Atlantic from otolith stable isotopes

Combining genetic markers with stable isotopes in otoliths reveals complexity in the stock structure of Atlantic bluefin tuna (Thunnus thynnus)

Individual assignment of Atlantic bluefin tuna in the northwestern Atlantic Ocean using single nucleotide polymorphisms reveals an increasing proportion of migrants from the eastern Atlantic Ocean

Contact Info

Product

Resources

About