Assessment of the barramundi fishery in Queensland, 1989-2007

The barramundi (Lates ca/carifer) is an important target species for commercial, recreational and Indigenous fishers across northern Australia. In Queensland, barramundi stocks from the Gulf of Carpentaria (GoC) and the east coast (EC) are managed separately. Updated assessments of both the Goe and EC stocks are reported here. The assessment used catch and effort information from both commercial (CFISH logbooks) and recreational (RFISH surveys) sources. The data were split into six different strata based on the genetic makeup of the stock, leading to six geographical regions with each having its own aggregated total commercial and recreational catch. The analysis proceeded in two stages. The first stage was a standardisation of the catch rate per unit of effort (CPUE) to obtain an estimate of the relative changes in abundance over time. The second stage was fitting a biomass dynamic model to estimate absolute stock biomass and management parameters such as maximum sustainable yield. The primary conclusion drawn from both the standardisation results and the dynamic modelling results is that the data are of insufficient quality to reliably estimate stock biomass or management parameters. This conclusion is based on a number of factors, including (but not limited to): • large fluctuations in the standardised catch rate, which would be biologically implausible if taken as a reliable index of abundance • an inability to find model parameters that lead to a good fit (unless certain parameters are taken past biologically plausible limits) • large uncertainty in parameters estimated from the surplus production model

Towards a flexible Decision Support Tool for MSY-based Marine Protected Area design for skates and rays

Peer-reviewed Paper. This is a pre-copyedited, author-produced version of an article accepted for publication in ICES Journal of Marine Science following peer review. The version of record Dedman, S., Officer, R., Brophy, D., Clarke, M., & Reid, D. G. (2017). Towards a flexible Decision Support Tool for MSY-based Marine Protected Area design for skates and rays. Ices Journal of Marine Science, 74(2), 576–587. https://doi.org/10.1093/icesjms/fsw147 is available online at: https://academic.oup.com/icesjms/article/74/2/576/2669563 & https://doi.org/10.1093/icesjms/fsw147.It is recommended that demersal elasmobranchs be managed using spatial proxies for Maximum Sustainable Yield. Here we combine escapement biomass—the percentage of the stock which must be retained each year to conserve it—with maps of predicted Catch Per Unit Effort (CPUE) of four ray species [cuckoo (Leucoraja naevus), thornback (Raja clavata), blonde (Raja brachyura), and spotted (Raja montagui)], created using Boosted Regression Tree modelling. We then use a Decision Support Tool to generate location and size options for Marine Protected Areas to protect these stocks, based on the priorities of the various stakeholders, notably the minimisation of fishing effort displacement. Variations of conservation/fishing priorities are simulated, as well as differential priorities for individual species, with a focus on protecting nursery grounds and spawning areas. Prioritizing high CPUE cells results in a smaller closed area that displaces the most fishing effort, whereas prioritizing low fishing effort results in a larger closed area that displaces the least fishing effort. The final result is a complete software package that produces maps of predicted species CPUE from limited survey data, and allows disparate stakeholders and policymakers to discuss management options within a mapping interface

Defining value per unit effort in mixed métier fisheries

This is the author’s version of a work that was accepted for publication in Fisheries Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Fisheries Research, 165,pps 1-10, doi:10.1016/j.fishres.2014.12.007Value achieved from time spent at sea is a central driver of fishing decisions and fishing behaviors. Value per unit effort (VPUE) is an important indicator of economic performance in itself and a useful metric within integrated mixed fisheries models. A time series of Irish first sale prices and total per trip landings values (VPT) highlight heterogeneity in fish prices and VPTs achieved by the Irish fleet spatially and temporally, as well as variability with species targeting. This investigation compared models to standardize fishing trip VPUE accounting for species targeting (métier groupings), engine power (a kW proxy for vessel size), seasonal and annual variability, fishing effort, and individual vessels (encompassing variability in vessel characteristics and skipper effects). Linear mixed effects models incorporating random vessel effects and within-group variance between métier groupings performed best at describing the variability in the dataset. All investigated factors were important in explaining variability, and thus important in standardizing VPUE. Models incorporating fishing days (days with reported fishing activity) and engine power as separate variables resulted in improved AIC values. Therefore, fishing days were considered to be the most appropriate effort measure to generate VPUE. The effort unit traditionally applied in measures of per unit effort, fishing hours, performed comparatively poorly in relation to VPT

Microplastic interactions with north atlantic mesopelagic fish

Microplastics in the marine environment are well documented, and interactions with marine biota have been described worldwide. However, interactions with vertically migrating fish are poorly understood. The diel vertical migration of mesopelagic fish represents one, if not the largest, vertical migration of biomass on the planet, and is thus an important link between the euphotic zone, transporting carbon and other nutrients to global deep sea communities. Knowledge of how mesopelagic fish interact and distribute plastic as a marine contaminant is required as these populations have been identified as a potential global industrial fishery for fishmeal production. Ingestion of microplastic by mesopelagic fish in the Northeast Atlantic was studied. Approximately 11% of the 761 fish examined had microplastics present in their digestive tracts. No clear difference in ingestion frequency was identified between species, location, migration behaviour, or time of capture. While ingesting microplastic may not negatively impact individual mesopelagic fish, the movement of mesopelagic fish from the euphotic zone to deeper waters could mediate transfer of microplastics to otherwise unexposed species and regions of the world's oceans

Microplastics in arctic polar waters: the first reported values of particles in surface and sub-surface samples

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment

Microplastics in arctic polar waters: the first reported values of particles in surface and sub-surface samples

Plastic, as a form of marine litter, is found in varying quantities and sizes around the globe from surface waters to deep-sea sediments. Identifying patterns of microplastic distribution will benefit an understanding of the scale of their potential effect on the environment and organisms. As sea ice extent is reducing in the Arctic, heightened shipping and fishing activity may increase marine pollution in the area. Microplastics may enter the region following ocean transport and local input, although baseline contamination measurements are still required. Here we present the first study of microplastics in Arctic waters, south and southwest of Svalbard, Norway. Microplastics were found in surface (top 16 cm) and sub-surface (6 m depth) samples using two independent techniques. Origins and pathways bringing microplastic to the Arctic remain unclear. Particle composition (95% fibres) suggests they may either result from the breakdown of larger items (transported over large distances by prevailing currents, or derived from local vessel activity), or input in sewage and wastewater from coastal areas. Concurrent observations of high zooplankton abundance suggest a high probability for marine biota to encounter microplastics and a potential for trophic interactions. Further research is required to understand the effects of microplastic-biota interaction within this productive environment

Correction: Gbm.auto: A software tool to simplify spatial modelling and Marine Protected Area planning.

[This corrects the article DOI: 10.1371/journal.pone.0188955.]

Advanced Spatial Modeling to Inform Management of Data-Poor Juvenile and Adult Female Rays

Chronic overfishing has depleted numerous elasmobranch stocks in the North East Atlantic, but addressing this issue has been hampered by management complications and lacking data. Spatial management approaches have thus been advocated. This work presents a novel application and further development of an advanced spatial modeling technique to identify candidate nursery grounds and spawning areas for conservation, by subsetting already limited data. Boosted Regression Tree models are used to predict abundance of juvenile and mature female cuckoo (Leucoraja naevus), thornback (Raja clavata), blonde (Raja brachyura), and spotted (Raja montagui) rays in the Irish Sea using fish survey data and data describing fishing pressure, predation and environmental variables. Model-predicted spatial abundance maps of these subsets reveal distinct nuances in species distributions with greater predictive power than maps of the whole stock. These resulting maps are then integrated into a single easily understood map using a novel approach, standardizing and facilitating the spatial management of data-limited fish stocks