Demographic patterns of southern bluefin tuna, Thunnus maccoyii, as inferred from direct age data

Farley, Jessica; Davis, T. L. O.; Gunn, John; Clear, Naomi; Preece, Ann L.

doi:10.1016/j.fishres.2006.09.006

Cited by 31 publications

(35 citation statements)

References 15 publications

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“…Possibly, all marine fishes experience ontogenetic changes in habitat use or spatial distribution owing to active migratory or passive oceanographic processes. Examples include the use of mangrove habitats by juvenile fishes (Laegdsgaard & Johnson 1995), age partitioning of the world's oceans by bluefin tuna ( Farley et al 2007), passive and active processes determining spatial distributions of larval cod (Bradbury et al 2003) and the use of shallow embayments by juvenile halibut ( Fodrie & Mendoza 2006). Many of these fishes are ecologically and economically important and are being developed for industrial aquaculture production.…”

Section: Discussionmentioning

confidence: 99%

Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations

Krkošek

Gottesfeld

Proctor³

et al. 2007

Proc. R. Soc. B.

107

122

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3Oona River Resources Association, Oona River, British Columbia, Canada V0V 1E0Animal migrations can affect disease dynamics. One consequence of migration common to marine fish and invertebrates is migratory allopatry-a period of spatial separation between adult and juvenile hosts, which is caused by host migration and which prevents parasite transmission from adult to juvenile hosts. We studied this characteristic for sea lice (Lepeophtheirus salmonis and Caligus clemensi ) and pink salmon (Oncorhynchus gorbuscha) from one of the Canada's largest salmon stocks. Migratory allopatry protects juvenile salmon from L. salmonis for two to three months of early marine life (2-3% prevalence). In contrast, host diversity facilitates access for C. clemensi to juvenile salmon (8-20% prevalence) but infections appear ephemeral. Aquaculture can augment host abundance and diversity and increase parasite exposure of wild juvenile fish. An empirically parametrized model shows high sensitivity of salmon populations to increased L. salmonis exposure, predicting population collapse at one to five motile L. salmonis per juvenile pink salmon. These results characterize parasite threats of salmon aquaculture to wild salmon populations and show how host migration and diversity are important factors affecting parasite transmission in the oceans.

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Section: Discussionmentioning

confidence: 99%

Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations

Krkošek

Gottesfeld

Proctor³

et al. 2007

Proc. R. Soc. B.

107

122

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“…SBT at ages 2 and 3 are found north of 35°S in the central Indian Ocean in winter (Farley et al 2007, Bestley et al 2009). However, the fact that SBT at ages 2 and 3 are caught by the Japanese longline fishery in the area south of 35° S in July and August suggests that some of these individuals move south in the southern hemisphere winter.…”

Section: Foraging Ecology Of Sbt In the Open Oceanmentioning

confidence: 96%

“…SBT distribution shifts as individuals age: from age 0 to 1, SBT are found on the continental shelf, from age 2 to 4 they migrate seasonally between coastal and open-ocean habitats, and after age 5, they are found primarily in the open ocean (Caton 1991, Farley et al 2007). These shifts in the distribution of SBT lead to changes in the composition of their prey.…”

Section: Foraging Ecology Of Sbt In the Open Oceanmentioning

confidence: 99%

“…Most Japanese longline fleets left the Tasmania area in the mid-2000s because of the very low catch rates, but they have returned in recent years. The central Indian Ocean north of 35°S is the fishing ground for Taiwanese longline fleets targeting young SBT, and the spawning area south of Java, Indonesia, is the fishing ground for the Indonesian longline fleets (Farley et al 2007). Further diet research in these areas is warranted, and SBT sampling should be feasible because of the presence of these fishing fleets.…”

Section: Constraints Of the Present Study And Future Researchmentioning

confidence: 99%

“…SBT are distributed throughout the circumpolar area between 30° and 50°S in the Atlantic, Indian, and Pacific oceans (Caton 1991). SBT are a single stock, and their only known spawning area is in the tropical eastern Indian Ocean, southeast of Java, Indonesia (Shingu 1978, Grewe et al 1997, Farley et al 2007). Juvenile SBT grow in the coastal waters along the western and southern coasts of Australia, and migrate seasonally between the southern coast of Australia and the central southern Indian Ocean (Hobday et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Open-ocean foraging ecology of southern bluefin tuna Thunnus maccoyii based on stomach contents

Itoh

Sakai²

2016

Mar. Ecol. Prog. Ser.

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We investigated the foraging ecology of southern bluefin tuna Thunnus maccoyii in open-ocean habitats of temperate waters in the southern hemisphere by analyzing their stomach contents. Samples were collected from longline vessels over 15 yr (n = 4649). Of the prey, 51% by weight were cephalopods and 46% were teleosts. These values differ from those in the literature for other top predators in the open oceans, for which teleosts compose the largest portion of prey. The dominance of cephalopods also differs from the pattern for juveniles in previous studies in their coastal habitat, where most of the prey are teleosts. Thus, a distinct shift of prey occurs along with the habitat shift due to ontogenetic development. By weight, important prey were ommastrephid (18%), lycoteuthid (12%), and argonautid (1%) cephalopods and nomeid (8%, mainly Cubiceps caeruleus), paralepidid (7%), bramid (6%), and alepisaurid (6%) teleosts. The prey composition was relatively consistent among tuna sizes, sea surface temperatures, and years; changes in prey composition were due largely to differences in the cephalopod prey. Cephalopods belonging to the families Lycoteuthidae and Argonautidae contributed to the prey only off the southern coast of Africa and near Tasmania, respectively. Lycoteuthids occurred at lower sea surface temperatures than ommastrephids off the southern coast of Africa. Small ommastrephids were dominant in smaller tuna in the southeastern Indian Ocean. Our data provide basic information that will improve our understanding of the oceanic food webs in southern temperate waters.

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Evidence of separate subgroups of juvenile southern bluefin tuna

Chambers

Sidhu

O'Neill

et al. 2017

Ecology and Evolution

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Archival tagging studies of southern bluefin tuna (SBT , Thunnus maccoyii) have revealed that juveniles residing in the Great Australian Bight (GAB) over the austral summer undertake seasonal cyclic migrations to the southeast Indian Ocean and the Tasman Sea during winter. However, there remains disagreement about the extent of mixing between juvenile SBT regularly caught by longline fleets south of Africa and those observed in the GAB. Some researchers have argued that archival tag recoveries indicate most juveniles reside in the GAB over the austral summer. Others have suggested that recoveries of conventional and archival tags are better explained by a juvenile population consisting of separate groups on the eastern and western sides of the Indian Ocean with limited intermixing. We present analyses of catch and tag recovery data and re‐examine archival tagging studies. The evidence provided strongly favors the hypothesis of separate juvenile subgroups, or contingents, with limited intermixing. We draw some tentative conclusions about the nature of the putative contingents and discuss some implications of these findings for the interpretation of existing datasets and future research priorities. We also provide the first evidence that the migration choices of juveniles that summer in the GAB are influenced by fidelity to winter feeding grounds and suggest this helps explain the collapse of the surface fishery off New South Wales in the 1980s.

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Demographic patterns of southern bluefin tuna, Thunnus maccoyii, as inferred from direct age data

Cited by 31 publications

References 15 publications

Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations

Effects of host migration, diversity and aquaculture on sea lice threats to Pacific salmon populations

Open-ocean foraging ecology of southern bluefin tuna Thunnus maccoyii based on stomach contents

Evidence of separate subgroups of juvenile southern bluefin tuna

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