[MARMAM] New publication on diet composition and biomass consumption in harbour seals (Maria Sørlie)

Maria Sørlie miokul at gmail.com
Sat Sep 26 10:55:43 PDT 2020

Dear Marmam colleagues,

I hope everyone is staying safe and healthy during these challenging times.

My co-authors and I are pleased to share our article on harbour seal diet:
“Diet composition and biomass consumption of harbour seals in Telemark and
Aust-Agder, Norwegian Skagerrak”.


Maria Sørlie, Kjell Tormod Nilssen, Arne Bjørge & Carla Freitas (2020) Diet
composition and biomass consumption of harbour seals in Telemark and
Aust-Agder, Norwegian Skagerrak, Marine Biology Research, DOI:


To explore ecosystem dynamics and functions it is vital to obtain knowledge
on predator–prey relations. Harbour seals are piscivorous predators that
can come into conflict with fisheries. Recently, as the Skagerrak and
Kattegat population of harbour seals has increased, claims have emerged
that seals are depleting coastal cod populations. The diet of harbour seals
in Norwegian Skagerrak was investigated based on otolith identification
from scats. The overall seal diet included 20 different fish
species/groups. The most important prey (combined index Qi) were
haddock/pollack/saithe (32.7%), genus Trisopterus (Norway pout/poor
cod/bib, 12.5%), plaice (12.4%) and herring (10.0%). Plaice also had the
largest biomass (24.1%). Gadoids and pleuronectids comprised 88.6% of the
diet (combined index Qi) and 87.1% in terms of biomass. Cod constituted
0.7% (combined index Qi) of the overall diet and 2.3% in terms of biomass.
Fish length estimates showed that seals generally prefer small fish below
minimum allowed landing size. Estimated total amount of fish consumed was
315 tons per year and was dominated by non-commercial species. Annual cod
consumption was an estimated 7.1 tons, representing 5% of annual cod
landings, suggesting that competition between local fisheries and harbour
seals is limited.

Key words: Phoca vitulina, cod, Gadus morhua, feeding ecology, prey

The article is Open Access and can be downloaded via this link:


You can also email me for a pdf copy or if you have any inquiries at
miokul at gmail.com

I would like to extend my gratitude to readers of our work as well as
editors and reviewers for their contributions to the finished product.

Wishing everyone all the best,

Maria Sørlie


Maria Sørlie

Master of Marine Ecology from University of Agder, Department of Natural

University of Agder

P.O.Box 422

4604 Kristiansand



miokul at gmail.com



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