Environmental effects on cephalopod population dynamics: implications for management of fisheries
Rodhouse, PGK and Pierce, GJ and Nichols, OC and Sauer, WHH and Arkhipkin, AI and Laptikhovsky, VV and Lipinski, MR and Ramos, JE and Gras, M and Kidokoro, H and Sadayasu, K and Pereira, J and Lefkaditou, E and Pita, C and Gasalla, M and Haimovici, M and Sakai, M and Downey, N, Environmental effects on cephalopod population dynamics: implications for management of fisheries, Advances in Marine Biology, 67 pp. 99-233. ISSN 0065-2881 (2014) [Refereed Article]
Cephalopods are a relatively small class of molluscs (about 800 species), but they support
some large industrial scale fisheries and numerous small-scale, local, artisanal fisheries.
For several decades, landings of cephalopods globally have grown against a background
of total finfish landings levelling off and then declining. There is now evidence
that in recent years, growth in cephalopod landings has declined. The commercially
exploited cephalopod species are fast-growing, short-lived ecological opportunists.
Annual variability in abundance is strongly influenced by environmental variability,
but the underlying causes of the links between environment and population dynamics
are poorly understood. Stock assessment models have recently been developed that
incorporate environmental processes that drive variability in recruitment, distribution
and migration patterns. These models can be expected to improve as more, and better,
data are obtained on environmental effects and as techniques for stock identification
improve. A key element of future progress will be improved understanding of trophic
dynamics at all phases in the cephalopod life cycle. In the meantime, there is no routine
stock assessment in many targeted fisheries or in the numerous by-catch fisheries for cephalopods. There is a particular need for a precautionary approach in these cases.
Assessment in many fisheries is complicated because cephalopods are ecological
opportunists and stocks appear to have benefited from the reduction of key predator
by overexploitation. Because of the complexities involved, ecosystem-based fisheries
management integrating social, economic and ecological considerations is desirable
for cephalopod fisheries. An ecological approach to management is routine in many
fisheries, but to be effective, good scientific understanding of the relationships between
the environment, trophic dynamics and population dynamics is essential. Fisheries and
the ecosystems they depend on can only be managed by regulating the activities of the
fishing industry, and this requires understanding the dynamics of the stocks they exploit.
cephalopods, population dynamics, environment, fluctuations, stock assessment, forecasting, management, governance