New historical data for long-term swordfish ecological studies in the Mediterranean Sea

Brian R Mackenzie,Pierpaolo Consoli,Franco Andaloro,Pietro Battaglia,Piero Addis,Gianluca Sarà,Teresa Romeo

doi:10.5194/essd-13-5867-2021

Abstract

Abstract. Management of marine fisheries and ecosystems is constrained by knowledge based on datasets with limited temporal coverage. Many populations and ecosystems were perturbed long before scientific investigations began. This situation is particularly acute for the largest and commercially most valuable species. We hypothesized that historical trap fishery records for bluefin tuna (Thunnus thynnus Linnaeus, 1758) could contain catch data and information for other, bycatch species, such as swordfish (Xiphias gladius Linnaeus, 1758). This species has a long history of exploitation and is presently overexploited, yet indicators of its status (biomass) used in fishery management only start in 1950. Here we examine historical fishery records and logbooks from some of these traps and recovered ca. 110 years of bycatch data (1896–2010). These previously neglected, but now recovered, data include catch dates and amounts in numbers and/or weights (including individual weights) for the time period before and after major expansion of swordfish fisheries in the Mediterranean Sea. New historical datasets such as these could help understand how human activities and natural variability interact to affect the long-term dynamics of this species. The datasets are online and available with open access via three DOIs, as described in the “Data availability” section of the article.

Highlights

Marine populations, species, and ecosystems were exploited for goods and services for long periods of time before scientific records of this exploitation were available
We hypothesized that historical trap fishery records for bluefin tuna (Thunnus thynnus Linnaeus, 1758) could contain catch data and information for other, bycatch species, such as swordfish (Xiphias gladius Linnaeus, 1758)
Sustainability objectives and actions based on short contemporary time perspectives (e.g., 2–3 decades, as is typical for many marine ecological time series) may be an insufficient basis on which to make management decisions regarding recovery to former states (Caswell et al, 2020; Engelhard et al, 2016; Jackson et al, 2001)

Summary

Introduction

Species, and ecosystems were exploited for goods and services for long periods of time before scientific records of this exploitation were available. The written scientific record of changes in such populations and systems can, and does in many cases, underestimate the degree to which society has impacted abundances, sizes, diversity or ecosystem functioning (Fortibuoni et al, 2010; Lotze et al, 2014; MacKenzie et al, 2011; Pauly, 1995). Sustainability objectives and actions based on short contemporary time perspectives (e.g., 2–3 decades, as is typical for many marine ecological time series) may be an insufficient basis on which to make management decisions regarding recovery to former states (Caswell et al, 2020; Engelhard et al, 2016; Jackson et al, 2001).

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Conclusion