A novel spatial risk assessment framework is proposed, based on the Spatially Explicit Fisheries Risk Assessment (SEFRA) and the Sustainability Assessment for Fishing Effects (SAFE). Risk is the probability that exploitation exceeds the Impact Sustainability Threshold (IST). Exploitation is estimated from the catchability and effort, using prior information on either the catchability or the population size. It is applied to shark and turtle species with different data characteristics.

As part of the development of spatially explicit fisheries risk assessment methodologies for chondrichthyans, spatial distribution modelling methodologies were tested on carpet shark, school shark, great white shark, and green turtle as well as on one simulated dataset. Eight recommendations were made for future distribution models including the need to model a year x space interaction as well as both the probability of presence and catch rate, and the usefulness of simulations.

This project has updated and characterised protected shark and ray fishery captures in New Zealand waters to the 2021 fishing year. Some protected species (whale shark, oceanic whitetip shark, deepwater nurse shark, and manta ray) were infrequently recorded. White shark, basking shark, and spinetail devil rays were more regularly observed and reported and additional analyses were completed to assess trends and factors that may increase risk of capture.

This review assesses the feasibility of a deepwater shark tagging programme in New Zealand waters. Firstly, it provides a general overview of current knowledge on deepwater shark age and growth, movement and habitat use, and post-release survival. Secondly, the report discusses tagging study designs and application. Lastly, an assessment gives options for a deepwater shark tagging programme in New Zealand.

Vector Autoregressive Spatio-Temporal (VAST) models were applied to research trawl survey and environmental data to provide updated information on stock status for seven deepwater sharks. Deepwater sharks were found to be ubiquitous around New Zealand, with each species shown to have a unique distributional pattern. Deepwater shark “hotspots” in New Zealand waters were identified (e.g., Puysegur). There was little evidence to suggest any temporal or spatial changes in distribution or abundance.

The accuracy of at-sea identification of six species of deepsea sharks by MPI observers was determined by NIWA using photographs taken at the time of sampling. DNA barcoding analysis was also used to identify specimens that lacked photographs, using muscle tissues taken by the observers from each shark specimen. The six species sampled in the study were:
• Seal shark Dalatias licha, BSH
• Leafscale gulper shark Centrophorus squamosus, CSQ
• Owston’s dogfish Centroscymnus owstonii, CYO
• Longnose velvet dogfish Centroselachus crepidater, CYP
• Baxter’s lantern dogfish Etmopterus granulosus, ETB
• Plunket’s shark Proscymnodon plunketi, PLS

The Ministry for Primary Industries (MPI) is developing a risk assessment framework to identify the nature and extent of risks to chondrichthyan populations. This project aims to fill some of the knowledge gaps for some of the high-risk, non-Quota Management System species to reduce the level of uncertainty in the risk assessments of those species, and to provide information on their productivity that can then be used as inputs into future quantitative risk assessments. The species included in this study were seal shark (Dalatias licha), Owston’s dogfish (Centroscymnus owstonii), longnose velvet dogfish (Centroselachus crepidater), and Plunket’s shark (Scymnodon plunketi). Specimens and data were collected aboard commercial fishing vessels and research vessels, and integrated with existing data and specimens held by NIWA.

Age and growth were estimated for carpet shark, common electric ray and blind electric ray from growth increments on their vertebrae and eye lenses. All three species grow moderately fast, and longevity is low to moderate compared with other elasmobranchs. Length and age at maturity, length at birth/hatching, and litter size were estimated. The length of the gestation period, and whether females have a resting period between pregnancies, are poorly known.

The potential impacts of the historical removal of top shark, finfish and mammalian reef predators on rocky reef ecosystems in the Hauraki Gulf are explored with qualitative modelling. The inclusion of small/medium size sharks had the most predictable impacts with highly certain negative impacts on the abundance of small/large lobsters, and highly certain increases of abundance of large predatory invertebrates, and macro-invertebrate predatory fish (e.g. snapper).

New Zealand adopted a revised National Plan of Action for the Conservation and Management of Sharks (NPOA-Sharks 2013) in January 2014. The NPOA-Sharks established a risk-based approach to prioritising management actions. This report details outcomes from a qualitative (level 1) risk assessment (RA), generated by an expert panel (and data informed where possible), which assessed the risk to all New Zealand chondrichthyes taxa from commercial fishing.

This report documents the collation, summarising and plotting on maps of distributional information on commercial catches, fishing effort, and catch-per-unit effort for all of New Zealand’s shark, ray and chimaera species. The five-year period October 2008 to September 2013 was used to plot the distribution of recent commercial catches, and a longer term perspective was provided by trawl catches made during the fishing years 1989−90 to 2007−08.

Systematic literature review addressing methods of reducing shark catch rates on longline fishing gear. Gear technology as well as operational and environmental variables were evaluated as potential elasmobranch bycatch reduction methods for use in New Zealand commercial longline fisheries. Methods of mitigating shark bycatch that ranked highest in this assessment were nylon leaders, large hooks and squid bait. Circle hooks appeared to increase shark retention but may complement nylon leaders by improving the odds of survival for animals that bite off the leader.

Results are presented from 97 101 stomachs of highly migratory species caught on surface longlines around New Zealand from 1994 to 2012. Dietary items are tabulated for 26 species and analysed in detail for 13 of these (ie. mako, porbeagle, and blue sharks, longsnouted and shortsnouted lancetfish, moonfish, Ray’s bream, albacore, butterfly, yellowfin, bigeye, and southern bluefin tunas, and swordfish). Within- and between-species dietary differences are discussed.

Basic demographic information necessary to characterise the productivity of two species of deepwater sharks, shovelnose dogfish Deania calcea and leafscale gulper shark Centrophorus squamosus in New Zealand waters was developed through analysis of age, growth, reproduction, and survey biomass trends from the collections on the Chatham Rise and Sub-Antarctic plateau.

To inform a review of the NPOA-Sharks, 107 research and monitoring studies carried out on cartilaginous fishes were reviewed. Most studies were on genetics, distribution and movement, catches and CPUE, and trawl surveys. Eighty-three of the 119 known species occurred in at least one study, and 36 species occurred in none. The achievements of the NPOA are assessed in relation to the actions specified in the plan. Recommendations are made for research to complete actions that were not achieved.