Spatial and Temporal Variability of Parasite Communities: Implications for Fish Stock Identification

Juan F Espínola-Novelo,Marcelo E Oliva

doi:10.3390/fishes6040071

Abstract

The spatial and temporal variability of parasite communities have received little attention when used as biological tags for identifying fish stocks. This study evaluated the potential spatial and temporal variability of the parasite communities affecting three marine fish species collected between 1993 and 2017. To avoid the potential effect of host age in parasite communities, individuals of similar ages were selected: 1123 Engraulis ringens (12–24 months old), 1904 Trachurus murphyi (24–36 months old), and 630 Merluccius gayi (36–48 months old). Most taxa show differences in the prevalence at the spatial and temporal scales, but the prevalence of some larval endoparasites remains constant at the temporal scale. At the spatial scale, an analysis of similarity (ANOSIM) showed differences in the parasite communities of three species; a canonical analysis of principal coordinates (CAP) showed low values of correct allocations (CA; ≈50%) and values of allocation due to chance (AdC) were lower than the CA. At the temporal scale, an ANOSIM showed differences between the three species. A CAP showed low values of CA (≈50–60%) and the AdC was always lower than CA. Samples at the spatial scale were well allocated to their localities or nearby localities, suggesting a spatial stability. Samples from different years were not well discriminated, suggesting temporal variability. Therefore, in studies regarding parasites as a tool for stock identification, temporal variability must be taken into account.

Highlights

Fishery management units are spatially defined by geographic or fishing grounds, but conventional stock assessment models assume that a fishery resource is a single, homogeneous population [1] with similar population parameters such as growth rate, recruitment, maturity and mortality; in addition, young fish in a group are produced by previous generations of the same group [2]
Despite the potential spatial and temporal variability in parasite fauna being a key issue in fish stock identification, such variability has received much less attention [14,15,16]
Of the 7142 individuals belonging to the three host species, a subsample of 3687 individuals were selected, including 1123 E. ringens (12 to 24 months old; range size 11.3–15.7 cm total length (TL)), 1904 T. murphyi (24 to 36 months old; range size 21.7–29.5 cm fork length (FL)) and 630 M. gayi (36 to 48 months old; range 37.3–45.6 cm TL)

Summary

Introduction

Fishery management units are spatially defined by geographic or fishing grounds, but conventional stock assessment models assume that a fishery resource is a single, homogeneous population [1] with similar population parameters such as growth rate, recruitment, maturity and mortality; in addition, young fish in a group are produced by previous generations of the same group [2]. The complexities of marine ecosystems present many challenges for defining population structures; a variety of tools have been developed for stock identification, including: physical and electronic tags; morphometric and meristic variation; morphology and/or the chemical composition of otoliths; genetic molecular analysis; and parasite burdens [1]. Since the pioneering studies [5,6] to the present [7,8,9], the criteria for using parasites as biological tags (BT) for stock identification have changed and evolved [10,11]. Despite the potential spatial and temporal variability in parasite fauna being a key issue in fish stock identification, such variability has received much less attention [14,15,16]

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Discussion

Conclusion