A review of recent studies on the life history and ecology of European cephalopods with emphasis on species with the greatest commercial fishery and culture potential

Abstract

With the depletion of many commercial fish stocks and an increasing demand for marine protein for human consumption, cephalopods have become more important as a fishery resource. In EU waters, cephalopod stocks are not routinely assessed and exploitation of these species by large-scale fisheries is largely unregulated. For sustainable exploitation, adequate assessment and scientifically-supported management strategies are needed. However, there is still a lack of data on stock status and inadequate knowledge of the life history and ecology of these species. The present review examined more than 200 scientific articles, on life history and ecology of European cephalopods, published since 2013. It describes recent contributions to knowledge in the context of previously identified research priorities, along with recent advances towards sustainable fishing and aquaculture. It also identifies outstanding knowledge gaps. While some priority areas, such as the development of the species identification guides and evaluation of climate change impacts on cephalopods, have seen significant advances, other challenges remain for the future. These include monitoring of the life history traits and fishery status for the main commercially exploited species in the area, implementation of improved species identification methods during scientific surveys and fisheries monitoring, development of tools to identify stock units, and the study of the environmental and anthropogenic impacts on the stocks of cephalopods inhabiting European waters.

Introduction

Wider recognition of cephalopods as key elements of marine ecosystems (Gasalla et al., 2010; de la Chesnais et al., 2019), evidence of increasing cephalopod abundance (Doubleday et al., 2016), and their potential to replace traditional fishery resources (Caddy and Rodhouse, 1998; Hunsicker et al., 2010; Rodhouse et al., 2014) have led to increased interest in these animals from the scientific community (e.g. Arkhipkin et al., 2015; Jereb et al., 2015). However, in European waters, cephalopods continue to be considered as minor fishery resources, not covered by the EU Common Fisheries Policy. While cephalopods are targeted by many small-scale fisheries, in most large-scale fisheries they are landed as a bycatch. Consequently, fished stocks are not well defined, monitoring of their status is limited and there is no routine assessment of stock status. There are no quota limits for cephalopod catches, although some EU countries specify minimum landing sizes and many directed small-scale fisheries are heavily regulated (see Pierce et al., 2010; Jereb et al., 2015).

A comprehensive review by Jereb et al. (2015) identified various knowledge and implementation gaps hindering the achievement of sustainable fisheries and culture of the main cephalopod resource species in European seas. These gaps (not all applying to all species) included (i) environmental effects on life history, distribution and abundance, including effects of climate change; (ii) age estimation techniques; (iii) basic life history traits; (iv) inferences on life history and ecology from studies of trace element and isotope composition of hard structures; (v) stock assessment; (vi) diet and nutrition.

Here, we review recent publications on life history, ecology, and fisheries of a key cephalopod species exploited in European seas to assess progress in filling these gaps. The following species were chosen for review based on the level of (or potential for) commercial exploitation and their distribution: octopuses – Octopus vulgaris, Eledone cirrhosa, Eledone moschata; cuttlefishes – Sepia officinalis, S. elegans and S. orbignyana; sepiolids – Sepietta oweniana and squids – Loligo vulgaris, Loligo forbesii, Alloteuthis subulata, Alloteuthis media, Illex coindetii, Todarodes sagittatus, Todaropsis eblanae, Ommastrephes caroli¹ and Gonatus fabricii.