This project is quantitative and will focus on analysis of existing data.
The productivity of fish, i.e. the recruitment of young fish1 into the population, is often the most important factor in determining population dynamics. Fisheries tend to remove old and large individuals2 from the population. These old and large individuals tend to contribute disproportionally toward productivity3–5, but their importance is debated6,7. To shed further light on the role of large spawners on population productivity, this suggested master project will investigate the role of large spawners in Atlantic cod (Gadus morhua) populations in the North Atlantic Ocean, following a recent approach4. The work will utilize existing data on stock size and structure and recruitment for different stocks where data is available (e.g. ICES databases). It may also be possible to extend the work to include e.g. Haddock (Melanogrammus aeglefinus). The details of the project will be developed by the student and the supervisor(s).
Refs.
1. Gaillard, J. M., Coulson, T. & Festa-Bianchet, M. Recruitment. Encycl. Ecol. Five-Volume Set 2982–2986 (2008) doi:10.1016/B978-008045405-4.00655-8.
2. Barnett, L. A. K., Branch, T. A., Ranasinghe, R. A. & Essington, T. E. Old-Growth Fishes Become Scarce under Fishing. Curr. Biol. 27, 2843-2848.e2 (2017).
3. Barneche, D. R., Ross Robertson, D., White, C. R. & Marshall, D. J. Fish reproductive-energy output increases disproportionately with body size. Science (80-. ). 360, 642–645 (2018).
4. Ohlberger, J., Langangen, ?. & Stige, L. C. Age structure affects population productivity in an exploited fish species. Ecol. Appl. 1–13 (2022) doi:10.1002/eap.2614.
5. Hixon, M. A., Johnson, D. W. & Sogard, S. M. BOFFFFs: on the importance of conserving old-growth age structure in fishery populations. ICES J. Mar. Sci. 71, 2171–2185 (2014).
6. Brunel, T. Age-structure-dependent recruitment: A meta-analysis applied to Northeast Atlantic fish stocks. ICES J. Mar. Sci. 67, 1921–1930 (2010).
7. Andersen, K. H., Jacobsen, N. S. & van Denderen, P. D. Limited impact of big fish mothers for population replenishment. Can. J. Fish. Aquat. Sci. 76, 347–349 (2019).