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This study aimed to characterise the recreational harvesting of wedge clams (Donax trunculus) in the Algarve coast (southern Portugal) and estimate its annual catches by recreational harvesters (RHs). For this purpose, 50 harvesting surveys were performed along the sandy intertidal during one-year (May 2022 - April 2023), roughly on a weekly basis during suitable tidal ranges (≤ 1.0 m). Overall, RHs were gender-balanced and older harvesters (≥ 65 years-old) prevailed. RHs were clearly more numerous from late spring to summer, especially in August, with most RHs collecting wedge clams with foot / hand and only a minority (≈20 %) also using a shrimp-net. RHs catches comprised mostly D. trunculus below the minimum conservation reference size (MCRS = 25 mm in shell length) legally stipulated for this species. The estimation of RHs annual catches of D. trunculus was based on standardised catches per harvester (number and weight hour−1), extrapolated using the total number of RHs and suitable tides for wedge clams recreational harvesting during the one-year study period. Collecting and processing geolocated data on RHs activity allowed mapping the spatial-temporal distribution of the recreational harvesting effort targeting wedge clams, further confirming the importance of spatial data as a support tool for management and decision-making processes. This study further confirmed the need to raise awareness and inform RHs about the best harvesting practices, aiming ultimately to improve the assessment and promote the long-term sustainable management of this recreational activity and shellfish resource.

Catch allocation models can split aggregated mixed-species catches into individual species for stock assessments and fisheries management. In this paper, we evaluate a suite of these models for splitting mixed ‘trawl whiting’ catches into eastern school whiting (Sillago flindersi) and stout whiting (S. robusta) allocations for a commercial ocean prawn trawl fishery in New South Wales (NSW), Australia. Accuracy of the models was evaluated against a scientific observer survey which accurately recorded species catches, and we compared the modelled allocations to an existing coarse ‘rule-based’ allocation. There was no single best structure for the allocation model, but the most successful models included depth as a covariate because this helped split species along habitat preferences. The model-based allocations reduced trip-level error by around 40 % compared to the existing rules, and removed an existing bias in total catch estimates. This led to altered time series of catches and catch-per-unit-effort, especially for northern zones. When data were analysed for the entire NSW region, the catch allocation process (existing or modelled) had little impact on resulting indices of relative abundance for each whiting species, even when using a spatio-temporal standardization model. This was likely due to changes affecting scale rather than trend and our indices being rescaled to better compare time periods. Therefore, past stock assessments relying on statewide indices derived from existing rule-based allocations are likely reliable. Nevertheless, the modelled allocations were more accurate at a local and zonal scale, which will enable analyses with a finer spatial resolution in future stock assessments. Additional observer surveys are an important tool for ongoing improvement and validation of our allocation models.

Pacific bluefin tuna (Thunnus orientalis, PBF), a highly migratory and commercially important species, faces intense fishing pressure. Taiwanese PBF catches, which reached a nadir in 2012, gradually increased from 2014 onwards, culminating in a dramatic fivefold surge after 2019. This study analyzed the adult population from PBF landings in Taiwan from 2010 to 2023 to inform fisheries management. We found a strong correlation between declining juvenile catches in Japanese troll or purse seine fishery and increasing adult catches in Taiwanese and Japanese longline fishery, with a 7–9 year lag. Age estimation, using otolith annuli and age-length keys, revealed a temporal shift in age composition. Despite the substantial increase in Taiwanese catch size, the average age of landed PBF decreased. The spawning stock, previously dominated by older individuals (14–18 years), now primarily consisted of younger fish (8–12 years). Prior to 2014, most PBF measured between 220 and 240 cm in fork length; after 2017, this range generally decreased to 200–220 cm. Permutation test using fish size and otolith direct ageing data suggested a lower mean fork length at age for the PBF landed in the recent years compared to earlier years. Furthermore, a linear mixed model showed a relationship between fork length and fishing year, indicating a consistent decrease in fork length across all age groups. These results suggest that reduced fishing pressure on juvenile PBF (0–1 years old) has allowed more individuals to reach adulthood, contributing to the observed recovery of the spawning population. These findings provide valuable insights into the effective fishery management and PBF stock rebuilding in Taiwan and other regions.

The widespread use of drifting fish aggregation devices (FADs) in tuna purse seine fisheries since the mid-1990s has raised sustainability concerns due to increased fishing mortality of unwanted species, such as small-sized tunas and silky sharks (Carcharhinus falciformis, FAL). A better understanding of ways to mitigate the catch unwanted species while increasing the catch of target species is critical for developing ecosystem-based management approaches. Here, we analyzed fisheries logbook data and scientific observer records of 345 FAD-associated fishing sets collected in the Western and Central Pacific Ocean to assess the influence of spatial-temporal strategies and fishing practices on the catch composition. Results demonstrate that technical adjustments can enhance the potential sustainability of tuna purse seine fisheries. Especially, small-sized tuna catches were concentrated in northern and eastern regions (2°N–6°N, 170°E–175°E), while FAL bycatch exhibited a more widespread distribution. Fishing practices factors, such as the duration of the purse seine gear set (∼9 min) and the time of the set relative to sunrise (∼30 min); substantially increased tuna catches while minimizing small-sized tuna catches. Seasonal analysis revealed that the pre-closure period (January to June) positively impacted tuna catches and reduced small-sized tuna catches. Moreover, FADs submerged structure at depths of 80 m stabilized tunas and FAL, while small-sized tunas tended to associate with deeper structures (90 m).