Integrating fish and parasite data as a holistic solution for identifying the elusive stock structure of Pacific sardines (Sardinops sagax)

Abstract

There is an urgent need to clarify how different stocks, or subpopulations of fish species, are vulnerable to fishing pressure and unfavorable ocean conditions because of the increasing demand on fisheries for human consumption. For marine fishes, the potential for high gene flow increases the difficulty in determining the number of subpopulations managed in a specific fishery. Although the use of molecular data has become a common method in the past 15 years to identify fish subpopulations, no single technique or suite of techniques has been established for fish stock structure studies. We review the use of fish morphometrics, artificial tags, fish genetics, parasite genetics, and parasites as biological tags to identify subpopulations of marine fishes with a focus on the Pacific sardine (Sardinops sagax) fishery off the west coast of North America. We suggest an integration of fish-and parasite-based techniques for future stock structure studies, particularly for pelagic fish species whose stock structure can be elusive. An integration of techniques may also resolve fish stock structure over small geographic areas by increasing the number of spatial and temporal scales studied simultaneously leading to methods for successful management of marine fish species.

Otolith shape variation provides a marker of stock origin for north Atlantic bluefin tuna (Thunnus thynnus)

“…This introduces uncertainty when assigning samples of unknown origin to their parent stock. Combining information from different sources in a holistic approach to stock identification can improve the accuracy of stock discrimination and provide greater insight into stock structure and the mechanisms that underlie it (Begg and Waldman 1999;Cadrin et al 2010;Baldwin et al 2012). Proper integration of the information provided by multiple stock markers requires careful consideration and coordination of sampling strategies (Abaunza et al 2008).…”

Parasitological evidence of stocks of Paralichthys isosceles (Pleuronectiformes: Paralichthyidae) at small and large geographical scales in South American Atlantic coasts

“…Furthermore, the inclusion of parasites in holistic approaches involving a broad spectrum of complementary techniques is increasingly recommended in stock identification studies (Begg and Waldman, 1999;Baldwin et al, 2012;Catalano et al, 2014;Cantatore and Timi, 2015). Indeed, the integration of parasites with other techniques may resolve fish stock structure over small geographic areas by increasing the number of spatial and temporal scales studied simultaneously leading to methods for successful management of marine fish species (Baldwin et al, 2012).…”

Helminth parasite communities of spotted rose snapper Lutjanus guttatus from the Mexican Pacific

“…For instance, similarity in parasite communities may decay with increasing distance between localities which could be related to discontinuities in the landscape or the probability that parasites species disperse among localities via host movements (Poulin, 2003;Timi et al, 2010). Such variation in composition and abundance of parasites provides information about the host population movements and structure which can be useful for the effi cient and sustainable management of a commercially exploited marine fi sh species (MacKenzie, 2005;Moore et al, 2011;Baldwin et al, 2012); however, this biological tool has received limited use in Mexican fi sheries (Violante-González et al, 2016). Therefore, the aim of this study was 2-fold: (1) to analyse the temporal and spatial variation of fi sh parasite populations and infracommunities of L. guttatus from two important fi shing localities in the Mexican Pacifi c; and (2) to evaluate the relationship between parasite load and fi sh body length.…”