Joe Scutt Phillips

• PhD Marine Ecology
• Senior Fisheries Scientist at The Pacific Community

Capture-mark-recapture methods (CMR) are a commonly used tool in species conservation and management for the estimation of demographic parameters in a population. However, biases in these estimates can occur due to the heterogeneity in processes influencing recapture data or the experimental design. We outline an approach to quantify and identify w...

Context Understanding tuna diet and its drivers can provide valuable insights into the dynamics of pelagic ecosystems and their capacity to adapt to environmental and human-induced stressors. Aims To reconstruct tropical tuna dietary histories by using different metrics of stomach fullness and to assess their association with fisheries-related, en...

Purse‐seine fishers using drifting fish aggregating devices (dFADs), mainly built with bamboo, plastic buoys, and plastic netting, to aggregate and catch tropical tuna, deploy 46,000–65,000 dFADs per year in the Pacific Ocean. Some of the major concerns associated with this widespread fishing device are potential entanglement of sea turtles and oth...

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 the world-wide tuna catch in 2019 and are one of the main sources of income in many Pacific island nations....

The Tuna Fisheries Assessment Report (TFAR) provides current information on the tuna fisheries of the western and central Pacific Ocean (WCPO) and the fish stocks (mainly tuna) that are impacted by them.

The general conclusions of this assessment are as follows: • The spawning potential of the stock has become more depleted across all model regions until around 2010, after which it has become more stable, or shown a slight increase. • Average fishing mortality rates for juvenile and adult age-classes have increased throughout the period of the ass...

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...

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...

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...

The tuna fisheries assessment report (commonly referred to as the "TFAR") provides current information on the tuna fisheries of the western and central Pacific Ocean and the fish stocks (mainly tuna) that are impacted by them. The information provided in this report is summary in nature, but a list of references (mostly accessible via the internet)...

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...

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 $\sim$100 km, despite interactions at this level potentially being important to both catch and distribution of tuna. For example, the associative...

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...

This paper describes the 2022 stock assessment of skipjack tuna Katsuwonus pelamis in the western and central Pacific Ocean.

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...

Post-release mortality experiments were undertaken on bigeye (Thunnus obesus) and yellowfin (T. albacares) tuna to assess potential post-release survival probabilities of conventional tagging on such individuals during commercial longline operations. Survival was estimated from the release of 32 tuna tagged with pop-up, satellite survivorship tags...

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...

Oceanic top predators, the marine ecosystems that support them and dependent socio-economic systems have been the subject of studies by researchers under the Climate Impacts on Oceanic Top Predators (CLIOTOP) regional programme since 2005. Research conducted under the programme has focused on how climate change is affecting the pelagic ocean, with...

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...

In an effort to increase purse seine fishing efficiency for tropical tunas, over 30,000 drifting Fish Aggregating Devices (dFADs) are deployed every year by fishers in the Western and Central Pacific Ocean (WCPO). The use of dFADs also impacts ecosystems, in particular through marine pollution and dFAD beaching. This paper presents the first estima...

Executive Summary This paper presents analyses of the PNA's fish aggregating device (FAD) tracking programme including: a description of the data processing required; a description of the spatio-temporal distribution of buoy deployments and number of FADs at sea; FAD densities including a correction procedure using ocean-current driven simulations;...

Uncertainty within the stock assessment for Western Central Pacific Ocean (WCPO) bigeye tuna has caused concern, particularly regarding the level of fishing mortality on small bigeye tuna associated with Fish Aggregating Devices (FADs), and the lack of understanding regarding the drivers of FAD association behaviour. A project was commissioned duri...

Data from tag seeding experiments have been used to estimate prior distributions for reporting rates for use in MULTIFAN CL (MFCL) assessments of tuna stocks in the Western Central Pacific Ocean. These prior distributions are used to minimise bias in assessments resulting from the non-reporting (or detection) of tag recoveries, and as such are a cr...

The increased use of drifting Fish Aggregating Devices (dFADs) by tuna purse seine fleets in recent years has supported considerable catches of these species. A greater understanding of the spatiotemporal dynamics of these objects as they drift with ocean currents is critical for understanding historical changes in fishing power, spatial management...

Foraging with tuna is a well-documented seabird strategy, referred to as facilitated foraging. However, despite this behaviour being considered almost obligatory in nutrient-poor tropical waters, little data exist on its relative importance to individual colonies. Therefore, to examine facilitated foraging under different patterns of nutrient avail...

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...

Maintaining the level of fish consumption in Pacific Island countries recommended for good nutrition as the populations of coastal communities grow, and as coral reefs are degraded by global warming and ocean acidification, will depend on small-scale fishers catching more tuna and other large pelagic fish. Concerted research and development by regi...

Executive Summary This paper presents preliminary data analyses from the PNA's FAD tracking programme, investigating research areas such as FAD densities in time and space, beaching events, dynamics around the WCPO FAD closure and some initial FAD life-history information. The 'cleaned' dataset discussed in this paper contained 7.4 million transmi...

Tuna fisheries catch over three million tonnes of skipjack tuna (Katsuwonus pelamis) each year, the majority of which come from purse-seine vessels targeting fish associated with man-made fish aggregating devices (FADs). A significant challenge for fisheries management is to maximize the efficiency of skipjack tuna catches whilst minimizing the byc...

Table A in S1 file. Summary of electronic tagging data used in this analysis. Figure A in S1 file. Varying surface-association threshold probability. Proportion of all time-series classified as “surface-associative”, by assumed threshold surface-association probability used in classification. Data are shown as simplified boxplots, with outliers of...

This information paper outlines the work plan and preliminary results from an Australian Research Council Linkage project that is developing an individual-based model (IBM) of WCPO skipjack. It is anticipated that there will be significant overlap between this project and certain recommendations of the WCPFC-SC. The SC11 summary report WCPFC12-2015...

The UK has 14 Overseas Territories (UKOTs): Anguilla; Bermuda; British Antarctic Territory; British Indian Ocean Territory; British Virgin Islands; Cayman Islands; Falkland Islands; Gibraltar; Montserrat; Pitcairn, Henderson, Ducie and Oeno Islands (commonly known as the Pitcairn Islands); St Helena, Ascension and Tristan da Cunha; South Georgia an...

Analysis of complex time-series data from ecological system study requires quantitative tools for objective description and classification. These tools must take into account largely ignored problems of bias in manual classification, autocorrelation, and noise. Here we describe a method using existing estimation techniques for multivariate-normal h...

Exploitation of tropical tunas in the western and central Pacific Ocean constitutes an industry generating over US$5 billion annually. As concern for the sustainability of fishing operations grows, there is an increasing need to explore the potential effects that small-scale movement behaviours, typically ignored in stock assessment, may have on la...

We present a study comparing Curvature Scale Space (CSS) representation with Shapelet transformed data with a view to discriminating between sagittal otoliths of North-Sea and Thames Herring using otolith boundary and boundary metrics. CSS transformed boundaries combined with measures of their circularity, eccentricity and aspect-ratio are used to...

In the Western and Central Pacific Ocean (WCPO), which accounts for over half of world tuna production, purse seine effort and catch on floating objects have increased significantly due to a rapid increase in the use of fixed and free-floating fish aggregation devices (FADs). FAD fishing has had an impact on the current status of the stocks of the...

We present a study comparing Curvature Scale Space (CSS) representation with Shapelet transformed data with a view to discriminating between sagittal otoliths of North-Sea and Thames Herring using otolith boundary and boundary metrics. CSS transformed boundaries combined with measures of their circularity, eccentricity and aspect-ratio are used to...

In the Western and Central Pacific Ocean (WCPO), which accounts for over half of world tuna production, purse seine effort and catch on floating objects have increased significantly due to a rapid increase in the use of fixed and free-floating fish aggregation devices (FADs). FAD fishing has had an impact on the current status of the stocks of the...

Most (84%) of the warming due anthropogenic climate change has been transferred to the oceans. This chapter outlines the causes and consequences of climate change and summarise future projections for ocean temperature rise, coral bleaching events and ocean acidification, and the associated uncertainties. This review largely focuses on marine ecosys...

The European eel (Anguilla anguilla) population has declined to levels that are now considered to be unsustainable unless strong conservation measures are introduced. The European Union (EU) has proposed stocking as one possible management measure to enhance the production of adult (silver) eels, and hence contribute to compliance with a river basi...