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Winter fisheries survey finds toothfish spawning in the Ross
First winter fisheries survey finds toothfish spawning in the Ross Sea
At the edge of
the advancing winter sea ice in the Ross Sea, a first-ever
winter fisheries survey has uncovered new secrets of the
Antarctic toothfish.
The New Zealand commercial
fishing vessel Janas, an ice strengthened longline
vessel owned and operated by Talley’s Ltd., New Zealand,
working with voyage scientists from the National Institute
of Water and Atmospheric Research in New Zealand (NIWA) and
the Italian National Programme of Antarctic Research (PNRA)
based at Institute of Marine Science (ISMAR, Genoa, Italy)
have collected the embryos of Antarctic toothfish for the
first time by using plankton nets to sample down to a depth
of 500m.
They have also fertilised eggs from captured adults in spawning condition, which provides a known start time to observe developmental rate.
The research is part
of a collaborative survey funded by the New Zealand Ministry
for Primary Industries, the Commission of the Conservation
of Antarctic Marine Living Resources (CCAMLR), and
Talley’s to study the reproduction of Antarctic toothfish,
their
population distribution, and their role in the Ross
Sea ecosystem.
NIWA fisheries scientist Dr Steve Parker said the discovery of developing toothfish embryos was important for several reasons. “Finding them documents the spawning season of the fish, confirms some areas where spawning was suspected to occur, and most importantly, provides information about the depth at which the drifting eggs reside in the water column. “
“This new information can be integrated with models of ocean currents to predict where the eggs and larvae will be transported as they develop and grow to become part of the juvenile population.”
Antarctic toothfish spawn under sea ice that extends more than 1000 km from the continent during the winter, and protecting them for most of the year from Weddell seals and killer whales, but also from scientists and fishers.
The winter voyage to the Ross Sea has taken more than a year to plan and is not an easy undertaking as those aboard have endured near constant darkness, vast expanses of sea ice, fierce seas, and temperatures far below zero to collect this elusive information. The 20 New Zealand crew of the Janasare experienced operators in these tough conditions, and Captain Jeff Pitt is a 15 year veteran fishing in the area.
All fishing in the Ross Sea is highly regulated by CCAMLR through catch limits, 100 percent observer coverage, and closed areas. The new information will be used to improve stock assessment and ecosystem models, advance management of the fishery
ENDS
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