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Habitat Use Throughout a Chondrichthyan's Life

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Version 2 2023-09-22, 01:42
Version 1 2021-11-16, 00:32
thesis
posted on 2023-09-22, 01:42 authored by Marquez, Melissa

Over the last few decades, much effort has been devoted towards evaluating and reducing bycatch in marine fisheries. There has been a particular focus on quantifying the risk to chondrichthyans, primarily because of their relatively high vulnerability to overfishing. A key part of risk assessment is evaluating the distributional overlap of the fish with the fisheries, where fish distribution is influenced by habitat use. I synthesised published observations of habitat use for different life history stages of chondrichthyans and hypothesised the associated catch composition in terms of fish sex, size, and maturity. I then searched for these catch compositions, and thereby locations, using New Zealand research vessel catch data. Results show that some life history stages and habitats for certain species can be identified, whereas others could not. Pupping ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), and Hydrolagus bemisi (GSP); nursery ground criteria were met for Callorhynchus milii (ELE), mating ground criteria were met for Callorhynchus milii (ELE), Hydrolagus novaezealandiae (GSH), Hydrolagus bemisi (GSP), and Harriotta raleighana (LCH); lek-like mating criteria were met for Hydrolagus novaezealandiae (GSH). For those life-history stage habitats not found, this may be because these are outside of the coverage of the data set (and likely also commercial fisheries), or because they do not actually exist for some chondrichthyans. On the basis of results, I propose to change the order of species in the New Zealand qualitative (Level 1) risk assessment, and rise the relative risk for Hydrolagus bemisi (GSP), given the species vulnerability of pupping grounds.

History

Copyright Date

2016-01-01

Date of Award

2016-01-01

Publisher

Te Herenga Waka—Victoria University of Wellington

Rights License

CC BY 4.0

Degree Discipline

Marine Biology

Degree Grantor

Te Herenga Waka—Victoria University of Wellington

Degree Level

Masters

Degree Name

Master of Science

ANZSRC Type Of Activity code

2 STRATEGIC BASIC RESEARCH

Victoria University of Wellington Item Type

Awarded Research Masters Thesis

Language

en_NZ

Victoria University of Wellington School

School of Biological Sciences

Advisors

Dunn, Matthew