Weever fish What the non-commercially exploited species can tell us about climate change Richard D.M. Nash 1, Audrey J.Geffen 1,2 & Henk Heessen 3 1. Port Erin Marine Laboratory, University of Liverpool, Isle of Man, British Isles 2. Department of Biology, University of Bergen, Norway 3 Netherlands Institute for Fisheries Research, IJmuiden, The Netherlands

Why have an interest in non-commercial species? However, changes in population size may be a consequence of fishing operations due to changes in habitat, ecosystem status and/or predator/prey relationships. Therefore one cannot just choose any species if one wants to try and look at possible effects of climate change on fish populations and areas. Changes in population size are not directly driven by commercial fishing.

The potential players et al.

Why the interest?

Lesser weever: Echiichthys vipera

Distribution of Lesser Weever Azores Canaries

Lesser Weever Classed as sub-tropical Not commercially exploited Very few predators Generally found on soft substrata Buries Spawns June to August Juveniles tend to be inshore and larger adults further offshore Tends to inhabit areas <50m depth

Wheeler, A Key to the Fishes of Northern Europe. It has no value to fishermen or anglers, and its chief impact on man is in being one of very few dangerous fishes in European seas. Totenese, E CLOFNAM. This species is considered the most dangerous of the European weevers, both for its poison and for its frequent occurrence very near to beaches.

North Sea 1.Annual changes in lesser weever distribution 2.Annual changes in lesser weever abundance 3.Changes in lesser weever length frequencies

IBTS

Lesser Weever: Latitude of population centre

Irish Sea 1.Distribution of lesser weever 2.Annual changes in population size of lesser weever 3.Annual variation in production of lesser weever 4.Changes in condition of lesser weever

Distribution of Lesser Weever in the Irish Sea

Simulated drift of plaice eggs and larvae, in the Irish Sea, after 31 and 61 days. Vertical movement behaviour patterns allowed for larvae. Data based on distribution of eggs and current patterns in Data from DEFRA/CEFAS funded research (MF0425) - plaice

Juvenile lesser weever (and plaice) and nursery grounds in the eastern Irish Sea Zone 1 Red Wharf Bay and Penmaenmawr Zone 3 Blackpool and Morecambe

One final thought In both areas there has been a decline in e.g. cod stocks. In both areas there has been a general increase in water temperature In both areas the lesser weever population appears larger than in the immediate past.

What can non-commercially exploited species tell us about climate change? Even these species are subjected to variability driven by commercial fishing operations – difficult to disentangle climate versus other driving factors. In many cases the data time series are too short to show clear trends in distribution, however, there are signs of increased population size of e.g. weever fish in to the North Sea. In the case of the Irish Sea population there was a clear trend in population size with the thermal regime, however, this breaks down in more recent years.