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Life history strategies of target fish species

Aims

Analyse growth, reproductive pattern, mortality and the distribution aspects of the life history of key benthic and benthopelagic fishes on the MAR and in the slope waters of the wider North Atlantic.

Descriptive studies


The basic knowledge of age, growth patterns, mode of reproduction and early life history of many deep-sea species is scarce, including for some target species of fisheries, hence basic descriptive analyses not driven by specific hypotheses will be essential.

Some hypotheses

1. The orange roughy and alfonsino may consist of isolated populations, contained in limited areas. The youngest ages will being found deeper than adults and the eggs and larvae are maintained, through advection and possibly physiological mechanisms, within their distributional areas.
2. It is energetically favourable (reduced expenditure and improved feeding opportunity) for roundnose grenadier to be found in the lee along seamounts and topographical features, away from currents.
3. Black scabbard is a solitary species that applies fast growth as an anti-predation mechanism.
4. Slow-growing species have, by necessity, anti-predation strategies.
5. The deepwater shark is a wide-ranging large top predator, but juveniles occupy deeper low-predation areas.
6. Chimaeras can be considered as representing an intermediate strategy between roundnose grenadiers and deepwater sharks in terms of reproduction and behaviour.
7. Conspecifics on the MAR and in adjacent slope waters have similar reproductive characteristics (gonad development, age ands size at first maturation, fecundity etc).

Strategy

Samples will be derived from MAR-ECO cruises, port sampling, and opportunistic efforts on e.g. fishing vessels operating on the MAR and along continental slopes. Port sampling will be essential to achieve seasonal patterns for selected species, e.g. black scabbardfish.

Technology

  • Sampling for analyses of ditribution and size-age structure: please see strategy /methods described for some of the other component projects within MAR-ECO.
  • Age determination by hard structures (otoliths, spines). Computer-assisted image analyses.
  • Maturity studies using advanced gonad histology and image analyses.

Schedule

Field phase and collection of reference data/material on slopes/islands: 2003-2005, Further analyses, dissemination, and provision of data to OBIS and advisory bodies (ICES, NAFO): 2005-2008.

Commitments

University of Bergen PhD studentship 2003-2006, sampling opportunities on Norwegian longliners 2003. Partner labour.

Partners

PI: maurice Clarke (Ireland)

Ivone Figueiredo, Gui Menezes, Sara Reis (Portugal), Inge Fossen, Anders Thorsen, Kristin Helle, Odd Aksel Bergstad (Norway), Sergio Iglesias, Pablo Duran Muoz (Spain), Sergey Evseenko, Tatjana Belyanina, Maria Shtaut, Diana Pobalkova, Vladimir Vinnichenko, Alexei Orlov (Russia), John D.M. Gordon (UK), Franz Uiblein (Austria), Pascal Lorance (France).

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