New Zealand Aquatic Environment and Biodiversity Report No. 216.

An individual-based population model was fitted to genetic capture-recapture data collected during 2001-16 from Māui dolphins (Cephalorhyncus hectori maui), to estimate population size and trends. The population is estimated to be declining despite declining mortality rates. Forward projections under various scenarios imply that a further reduction of anthropogenic mortality of at least 50% is required to arrest population decline and avert extinction, regardless of the main source of the mortality, which is suspected to be fisheries bycatch and/or disease.

New Zealand Aquatic Environment and Biodiversity Report No. 215. 18 p.

A Bayesian Māui dolphin population model was developed integrating information from genetic “mark-recapture” and population size estimates. Model runs incorporated estimates of historical annual deaths from commercial fisheries and toxoplasmosis obtained from a separate spatial risk assessment. These models were then used to simulate the effects of estimated threat-specific mortality rates on future population growth.

New Zealand Aquatic Environment and Biodiversity Report No. 214. 168 p.
(Manuscript 3334)

A spatial risk assessment of threats was undertaken for Hector’s and Māui dolphins, to inform a revised Threat Management Plan (TMP) for the species. A Bayesian risk model was developed using the spatially-explicit fisheries risk assessment (SEFRA) approach, incorporating revised estimates of Hector’s and Māui dolphin spatial density and intrinsic population growth rate. The risk model was used to estimate spatial overlap, annual deaths and risk for commercial fisheries and lethal non-fishery threats, including toxoplasmosis. Spatial overlap was estimated for other threats.

Francis, M.P.; Hoyle, S.D. (2019). Estimation of fishing effort in the Southern Hemisphere.

New Zealand Aquatic Environment and Biodiversity Report No. 213. 24 p.

This report estimates the high seas fishing effort expended in the Southern Hemisphere by the main methods likely to impact seabirds (surface and bottom longline, and trawl). Data were sourced from 10 Regional Fisheries Management Organisations. Effort totals are biased low (sometimes substantially) in some regions and times, although the degree of under-estimation has probably declined through time. These estimates will be used in a subsequent quantitative risk assessment of seabirds.

978-1-98-859461-3

(Manuscript 3308)

Alestra, T.; Gerrity, S.; Dunmore, R.A.; Marsden, I.; Pirker, J.; Schiel, D.R. (2019). Rocky reef impacts of the Kaikōura earthquake: quantification and monitoring of nearshore habitats and communities.
New Zealand Aquatic Environment and Biodiversity Report No. 212. 120 p.


Surveys along 130 km of coastline in the first sixteen months following the Kaikōura earthquake showed significant damage to intertidal benthic communities at all sites. Subtidal communities were impacted only at sites with uplift greater than 2 m. Taonga species such as paua and bull kelp were still present at most sites and showing signs of post-earthquake recruitment. This information provides a key baseline for management decisions and new research into long-term trajectories of recovery.

Manuscript 3269

This assessment presents bycatch estimates of seabirds in commercial trawl and longline fisheries in New Zealand’s Exclusive Economic Zone. The estimation relied on statistical models that used fishing effort and observer data up to the 2015–16 fishing year. Estimates for the latter fishing year included a total of 4517 (95% credible interval: 3760–5825) seabird captures in trawl and longline fisheries in New Zealand waters.

This report summaries annual estimates of bycatch levels of individual fish and invertebrate species in the trawl fisheries for arrow squid, hoki/hake/ling, southern blue whiting, jack mackerel, orange roughy, oreo, scampi, and the longline fishery for ling from 1990–91 to 2016–17. Total annual bycatch was estimated using a statistical model method, replacing a ratio estimator-based method used in previous iterations of this work.

A reassessment of population size and trends of Hutton’s shearwater following the 2016 Kaikōura earthquake and outlook for the species’ management.

D’Archino, R.; Neill, K.F.; Nelson, W.A.; Fachon, E.; Peat, C. (2019). New Zealand Macroalgae: Distribution and Potential as National Scale Ecological Indicators.

New Zealand Aquatic Environment and Biodiversity Report No.207. 217 p.

Canopy-forming macroalgae are internationally recognised as critical components of coastal ecosystems as primary producers, coastal buffers and provision of habitat. This report evaluates the use of large brown macroalgae as indicators of ecosystem health by: summarising the international and national literature; testing the responses of key species to stressors in culture; investigating a range of approaches to mapping and monitoring, including the use of drones and machine learning to analyse underwater videos.

Tuck, I.D.; Hewitt, J.E.; Bulmer, R.H. (2019). Monitoring Recovery of Benthic Fauna in Spirits Bay.

New Zealand Aquatic Environment and Biodiversity Report No. 206. 74 p.

This report describes changes in the benthic communities of Spirits Bay related to fishing pressure and environmental factors. Survey data were analysed from 2006, 2010 and 2017. Epifaunal and infaunal communities consistently identified year, habitat, depth and fishing effects. Weaker fishing effects were detected from recent surveys, where fishing effort was lower. Species identified as sensitive to fishing were previously identified as sensitive on the basis of life history and morphology.

A data driven bioregionalisation to underpin shellfish fisheries restoration, Nelson Bays, New Zealand

The main breeding population of New Zealand (NZ) sea lions (Otariidae: Phocarctos hookeri) at the Auckland Islands has declined by about 50% since the late-1990s. This population displays numerous indicators of nutritional stress, but the precise mechanisms of this stress (e.g., essential prey species and changes in their availability to NZ sea lions) remain poorly understood. This precludes a meaningful assessment of the effects of environmental change or indirect fishery effects on NZ sea lion populations.

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

Data from two surveys to characterise biogenic habitats identified through Local Ecological Knowledge interviews are reported. The results demonstrate that New Zealand’s continental shelf supports a diverse range of habitats and species, many of which have not yet been formally described by science. At selected sites, the key habitat-forming species were identified, and the invertebrate species composition and associated fish communities described over localized spatial scales, and depth ranges.

CatchMapper provides heat maps and spatial estimates of catch and effort anywhere in the EEZ for all types of commercial fishing except eel fishing. This report describes the fishing represented in CatchMapper from October 2007 to September 2016 as well as the procedures for building polygons for fishing events, apportioning trip landings to each event polygon, and the range of ways the values of each polygon can be classified, pooled, and cut into spatial catch estimates and maps.