Modelling Marine Predator Habitat Using the Abundance of Its Pelagic Prey in the Tropical South-Western Pacific

Aurore Receveur,Philippe Borsa,Anne Lebourges Dhaussy,Sophie Laran,Steven R Hare,Valerie Allain,Andreas Ravache,Eric Vidal,Frederic Menard,Henri Weimerskirch,Karen Bourgeois,Christophe Menkes

doi:10.1007/s10021-021-00685-x

Abstract

Understanding the ecological mechanisms underpinning distribution patterns is vital in managing populations of mobile marine species. This study is a first step towards an integrated description of the habitats and spatial distributions of marine predators in the Natural Park of the Coral Sea, one of the world’s largest marine-protected areas at about 1.3 million km2, covering the entirety of New Caledonia’s pelagic waters. The study aims to quantify the benefit of including a proxy for prey abundance in predator niche modelling, relative to other marine physical variables. Spatial distributions and relationships with environmental data were analysed using catch per unit of effort data for three fish species (albacore tuna, yellowfin tuna and dolphinfish), sightings collected from aerial surveys for three cetacean guilds (Delphininae, Globicephalinae and Ziphiidae) and foraging locations identified from bio-tracking for three seabird species (wedge-tailed shearwater, Tahiti petrel and red-footed booby). Predator distributions were modelled as a function of a static covariate (bathymetry), oceanographic covariates (sea surface temperature, chlorophyll-a concentration and 20 °C-isotherm depth) and an acoustically derived micronekton preyscape covariate. While distributions were mostly linked to bathymetry for seabirds, and chlorophyll and temperature for fish and cetaceans, acoustically derived prey abundance proxies slightly improved distribution models for all fishes and seabirds except the Tahiti petrel, but not for the cetaceans. Predicted spatial distributions showed that pelagic habitats occupied by predator fishes did not spatially overlap. Finally, predicted habitats and the use of the preyscapes in predator habitat modelling were discussed.

Highlights

Modelling the habitat of top predators is critical to understand their spatiotemporal dynamics and to develop appropriate conservation strategies
Non-targeted species such as cetaceans or seabirds are usually counted from boats or aircraft
Bathymetry is complex in the New Caledonia EEZ (Figure 1A), with deep waters in the north and the south-east ( 5 km), shallower waters in the south-western corner and south of the main island ( 3 km) and the deep New Hebrides trench in the east (> 7 km deep; Stewart and Jamieson 2018)

Summary

Introduction

Modelling the habitat (for example, thermal preference) of top predators is critical to understand their spatiotemporal dynamics and to develop appropriate conservation strategies. The way top predators are monitored largely varies among groups and can make the modelling of their habitat a challenging task. The abundance of commercially exploited species is often assessed using catch data (for example, Lan and others 2018), and that of non-target species, using by-catch data (for example, Escalle and others 2019) and on-board observer data (for example, Lopez and others 2003). Non-targeted species such as cetaceans or seabirds are usually counted from boats or aircraft. Movements of exploited and non-exploited marine predators are monitored using a variety of tags (for example, Block and others 2011; Abecassis and others 2015; Leroy and others 2016; Ravache and others 2020a). Behaviour (foraging, migrating, resting) can be identified at various spatial–temporal scales: from a few seconds to several years and from a few centimetres to thousands of kilometres

Methods

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Discussion

Conclusion