Diet of harbour seals in a salmon estuary in North-West Iceland

Abstract

The effect of harbour seal predation on salmonids has been frequently debated, although interactions between these species have never been thoroughly investigated in Icelandic waters prior to this study. We investigated the diet of harbour seals in a salmon estuary in NW Iceland between 2009 and 2011, using hard part analysis from collected faeces. No evidence of seal predation on salmonids was found in the study. The reconstructed weight and estimated energy content of prey species showed that flatfish was the most important species group, followed by Ammodytidae. The species group found in the highest proportion of samples during the three years combined was also Ammodytidae (45% of the samples). Ammodytidae, flatfishes and capelin dominated by numerical occurrences. However, inter- and intra-annual variation was found regarding the diet.

Áhrif afráns sela á laxfiska hefur verið umdeilt, og sjaldan rannsakað við íslenskar aðstæður. Við rannsökuðum fæðuval landsela á ósasvæði á Norðurlandi vestra árin 2009 til 2011 með kvarna- og beinagreiningu úr selasaursýnum. Við fundum engar vísbendingar um laxfiska í saursýnunum. Áætluð þyngd og orkuinnihald bráðtegunda leiddu í ljós að flatfiskar voru mikilvægastir í fæðu selanna, en næstmikilvægast var síli (Ammodytidae). Síli var einnig fæðutegundin sem fannst hlutfallslega mest í saurnum öll árin (45% sýna) og síli, flatfiskar og loðna voru ríkjandi hvað varðar fjöldi einstakra fiska. Breytileiki var þó nokkur á milli ára og einnig var árstíðabundin breytileiki í fæðuvali selanna.