Simon Nicol

The Pacific Community | SPC · Oceanic Fisheries Programme

Catch per unit of fishing effort (CPUE) is often used as an indicator of tuna abundance, where it is assumed that the two are proportional to each other. Tuna catch is therefore typically simplified in tuna population dynamics models and depends linearly on their abundance. In this paper, we use an individual-based model of tuna and their interacti...

Minimising the unintended capture of fish, marine mammals, reptiles, seabirds and other marine organisms is an important component of responsible fisheries management and for stabilising declines and rebuilding populations of threatened species. The analyses presented were designed to establish the first quantitative baseline of historical catches,...

The Tropical Pacific Ocean is characterized by its dominant zonal flow, strong climate dependence on the El Niño Southern Oscillation (ENSO) and abundant tuna stocks. Tuna fisheries in the West and Central Pacific Ocean accounted for 55 % of world-wide tuna catch in 2019 and are one of the main sources of income in many Pacific island nations. One...

Sample cross-contamination remains a pervasive issue in genetics and genomics. With growing reliance on molecular methods for managing marine resources, the need to ensure the integrity of tissue samples that underpin these methods has never been more pressing. We conducted an experiment on wild-caught bigeye tuna (Thunnus obesus) to assess cross-c...

Archival (data-storage) and telemetry (acoustic and radio) tags are commonly used to provide data on the behavior and physiology of organisms, as well as data on their surrounding environment. For fishes, it is often advantageous to implant tags in the peritoneal cavity (i.e., intracoelomic implantation). The literature on best practices is limited...

Large-scale, no-take marine protected areas (MPAs) have been established in several locations in the Pacific and expansion of such areas to reach 30% of the ocean area is actively promoted in some quarters. Justification for the establishment of large oceanic MPAs often includes the conservation benefits that they would bring for tuna stocks, which...

Catch and distribution of tuna in the ocean are typically investigated with ocean basin-scale models. Due to their large scale, such models must greatly simplify tuna behaviour occurring at a scale below ∼100 km, despite interactions at this level potentially being important to both catch and distribution of tuna. For example, the associative behav...

A variety of density-dependent and -independent processes have been proposed to influence natural mortality rates, potentially leading to variation through time. Processes of natural mortalities are rarely directly observed, making estimation of natural mortality rates difficult. Mark-recapture data allow estimation of total mortality rates, which...

Climate change is predicted to alter the distributions of tropical tuna stocks in the Pacific Ocean. Recent modelling projects significant future shifts in tuna biomass from west to east, and from national jurisdictions to high seas areas. As the distributions of these stocks change, the relevant regional fisheries management organisations (RFMOs)—...

In the Western and Central Pacific Ocean (WCPO), programmes of large-scale tagging experiments have been carried out on skipjack, yellowfin and bigeye tuna, to aid estimation of movement and mortality parameters through the stock assessment model MULTIFAN-CL. The integration of tagging data in this context includes critical assumptions about the pe...

Mark-recapture tagging data are adjusted prior to use in assessments of WCPO tropical tuna to account for tagging-induced mortality and tag shedding, which mitigates against downwards bias in fishing mortality estimates. A range of variables have been shown to impact the probability of recapturing tagged fish, including tagger experience and identi...

This preliminary study used DNA metabarcoding to test whether the stomach content and gut microbiome of tuna could be a viable near real-time monitoring tool for detecting composition and change in oceanic ecosystems. The gut content of skipjack (Katsuwonus pelamis, n=55) and yellowfin tuna (Thunnus albacares, n=46) captured in the Pacific Ocean du...

The current management of the bigeye tuna ( Thunnus obesus ) fishery in the Western and Central Pacific Ocean (WCPO) is based on a “single-stock” paradigm. We investigated the spatial and temporal distribution of the neutral and potentially adaptive genetic diversity in samples collected from waters near Micronesia, Marshall, Phoenix and Gilbert Is...

The impacts of climate change are expected to have profound effects on the fisheries of the Pacific Ocean, including its tuna fisheries, the largest globally. This study examined the combined effects of climate change on the yellowfin tuna population using the ecosystem model SEAPODYM. Yellowfin tuna fisheries in the Pacific contribute significantl...

Bycatch on pelagic tuna longlines has contributed to population declines in several far-ranging, oceanic species and presents a conservation challenge that area-based management tools are increasingly promoted to address. In January 2020 the Republic of Palau, concerned about the impacts of longline fishing in its waters, closed 80% of its exclusiv...

The Western and Central Pacific Fisheries Commission (WCPFC) has a responsibility to assess the impact of fishing on non-target species. In this report, we estimate the bycatch of the large-scale purse seine fishery operating primarily in tropical waters of the WCPFC Convention Area east of 140°E. These large vessels, typically greater than 500 ton...

Climate-driven redistribution of tuna threatens to disrupt the economies of Pacific Small Island Developing States (SIDS) and sustainable management of the world’s largest tuna fishery. Here we show that by 2050, under a high greenhouse gas emissions scenario (RCP 8.5), the total biomass of three tuna species in the waters of ten Pacific SIDS could...

Ecosystem models forced by future climate simulations outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5) simulate a substantial decline of tropical marine animal biomass over the course of the 21st century. Regional projections are however far more uncertain because of well-known biases common to most CMIP5 historical simulation...

Skipjack tuna ( Katsuwonus pelamis ) has historically been considered panmictic at the ocean basin scale because of the species’ life history and substantial absolute population size. However, recent advances in population genomics have enabled scientists to demonstrate population structure in other species that were likewise traditionally assumed...

Developing a typology of heterogeneous fishing practices through the use of métier analysis is a useful step in understanding the dynamics of fishing fleets and enabling effective implementation of management outcomes. We develop a non-hierarchical clustering framework to quantitatively categorize individual fishing events to a particular métier ba...

The giant ruby snapper, Etelis sp., attains the largest size of any lutjanid in the Indo-Pacific and is one of the most valuable species harvested from deep-water fisheries along the continental and insular shelf margins throughout its broad geographic distribution. Despite this species supporting important commercial, artisanal and subsistence fis...

This information Paper describes the pre-processing of tagging data prior to their integration into the 2020 stock assessments for yellowfin and bigeye tuna. The SC is advised to note: The adjustment to the process for selecting data and variables for use in the statistical models to estimate the effects of tagger experience, imprecise tag placemen...

This Information Paper applies an individual-based model (Ikamoana, Scutt Phillips et al. 2018) to understand the impact that spatial scale, location and differing oceanographic conditions may have on mixing assumptions for skipjack tuna tagged in the WCPO. Virtual tag releases for two archipelagic tag release locations in Papua New Guinea and an o...

These preliminary catch estimates should not be reproduced or cited without permission from SPC and / or WCPFC Executive Summary: This report updates regional estimates of longline catches, covering the full range of finfish, billfish, shark and ray, marine mammal and sea turtle species that have been recorded in longline observer data. The estima...

Tunas are the focus of significant fisheries in the Pacific Ocean, where landings of four species – skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) – constitute approximately 70 % of the global tuna catch. Stock assessments for skipjack, yellowfin and bigeye t...

Delineating the stock structure of highly-mobile, wide-ranging fishes subject to exploitation is a challenging task, yet one that is fundamental to optimal fisheries management. A case in point are stocks of skipjack tuna (Katsuwonus pelamis), yellowfin tuna (Thunnus albacares), bigeye tuna (Thunnus obesus) and albacore tuna (Thunnus alalunga) in t...

Risks to deepwater chondrichthyans (sharks, rays, and chimaeras) from fishing are poorly understood, particularly in areas beyond national jurisdiction. We adapted productivity-susceptibility analysis (PSA) and sustainability assessment for fishing effects (SAFE) to assess the vulnerability of 173 deepwater chondrichthyans to various demersal fishi...

The United Nations General Assembly has called for the adoption of conservation management measures to protect vulnerable marine ecosystems (VMEs) from significant adverse impacts outside of areas of national jurisdiction. In response, many regional fisheries management organizations (RFMOs) have implemented move-on rules triggered by encounter thr...

Minimizing fishing-induced mortality on bycatch and endangered, threatened or protected species is a necessity for fisheries managers. Estimating individual vessel bycatch rates by dividing the amount of bycatch by effort (nominal rate) can be biased, as it does not consider effort heterogeneity within the fleet and ignores prior knowledge of fleet...

In the Pacific Island region, marine resources make vital contributions to food security, livelihoods and economic development. Climate change is expected to have profound effects on the status and distribution of coastal and oceanic habitats, the fish and invertebrates they support and, as a result, the communities and industries that depend on th...

Projected population growth in Pacific Island countries, combined with their narrow resource base, declines in net food production per capita and growing reliance on imported foods will increase food insecurity. We examined whether policies requiring retention of edible, non-target catches by the Western and Central Pacific purse seine fishery coul...

In the past researchers wrote mainly articles and research papers in their specific field of study seen by professional readers in that field. Today, besides articles, researchers write many other types of documents and consider readers outside their circle. The visual design of the traditional research papers, so long taken for granted. A good vis...

Anthropogenic CO 2 emissions are causing global ocean warming and ocean acidification. The early life stages of some marine fish are vulnerable to elevated ocean temperatures and CO 2 concentrations, with lowered survival and growth rates most frequently documented. Underlying these effects, damage to different organs has been found as a response t...

Elevated seawater CO2 can cause a range of behavioural impairments in marine fishes. However, most studies to date have been conducted on small benthic species and very little is known about how higher oceanic CO2 levels could affect the behaviour of large pelagic species. Here, we tested the effects of elevated CO2, and where possible the interact...

Estimating the heritability and genotype by environment (GxE) interactions of performance-related traits (e.g., growth, survival, reproduction) under future ocean conditions is necessary for inferring the adaptive potential of marine species to climate change. To date, no studies have used quantitative genetics techniques to test the adaptive poten...

Most assessments of the effectiveness of river restoration are done at small spatial scales (<10 km) over short time frames (less than three years), potentially failing to capture large‐scale mechanisms such as completion of life‐history processes, changes to system productivity, or time lags of ecosystem responses. To test the hypothesis that popu...

Electronic monitoring (EM) consisting of on-board video imagery and on-shore analysis, offers an alternative or supplement to at-sea observer programs in commercial fisheries. In the western and central Pacific Ocean (WCPO), where observer coverage in most tuna longline fisheries has historically been <5%, the advent of EM has been perceived as a t...

• Conservation strategies for endangered species often include protection from harvest by humans. Correct species identification is paramount for this form of management to be effective. • Trout cod (Maccullochella macquariensis) is a threatened Australian freshwater fish, occupying habitats in the southern Murray–Darling basin. Trout cod, although...

Fishery performance is highly dynamic and depends on several environmental and non-environmental parameters such as changing temperature and ocean currents, fish behavior, changing market and economic conditions. Therefore, management tactics should be designed to be adaptive to respond to changing conditions. A robust adaptive and flexible managem...

The majority of the world's fisheries lack formal management and assessment due to limitations in data, management capacity, or both. Capacity-limited fisheries generally contain some combination of limited infrastructure, personnel or expertise which hampers the ability of fisheries administrations to develop, implement and maintain desired manage...

Fishery status reports 2018 provides an independent evaluation of the biological and economic status of fish stocks managed solely or jointly by the Australian Government. This 23rd edition of the Fishery status reports covers the biological status of 95 fish stocks across 22 fisheries, including those managed both solely and jointly by the Austra...

Bigeye tuna are targeted by longliners and caught incidentally by purse seiners in the tropical Pacific. The spawning biomass has been reduced significantly from unexploited levels, necessitating management action in both the western and central Pacific and eastern Pacific. Stock assessments of bigeye tuna rely primarily on data from the fisheries;...

Ocean acidification and warming are co-occurring stressors, yet their effects on early life stages of large pelagic fishes are not well known. Here, we determined the effects of elevated CO2 and temperature at levels projected for the end of the century on activity levels, boldness, and metabolic traits (i.e., oxygen uptake rates) in larval kingfis...

Ocean warming and acidification are serious threats to marine life; however, their individual and combined effects on large pelagic and predatory fishes are poorly understood. We determined the effects of projected future temperature and carbon dioxide (CO2) levels on survival, growth, morphological development and swimming performance on the early...

The distribution of marine species is often modeled using Eulerian approaches, in which changes to population density or abundance are calculated at fixed locations in space. Conversely, Lagrangian, or individual-based, models simulate the movement of individual particles moving in continuous space, with broader-scale patterns such as distribution...

Context There is concern that deer are shifting forests towards undesirable trajectories, and culling of deer is often advocated to mitigate these impacts. However, culling deer is expensive and sometimes controversial. To reliably ascertain whether such action is beneficial, management-scale experiments are needed. We conducted a management experi...

Deepwater tropical fisheries provide an important source of income and protein to Pacific and Indian Ocean coastal communities who are highly dependent on fish for food security. The development of quantitative assessments and management strategies for these deepwater fisheries has been hindered by insufficient biological and fisheries data. We exa...

Albacore is one of the most important commercially harvested species in the world’s oceans. Despite a long history of scientific research, there is no global review or synthesis of knowledge about the species across all oceanic regions. We analysed 613 published studies that report on albacore and summarize the current state of knowledge on biology...