Autumn distribution of Bristol Bay red king crab using fishery logbooks

Abstract

Spatial distributions of fished species must be well characterized to avoid local depletions, identify critical habitat, and predict and mitigate interactions with other fisheries. The Bristol Bay red king crab (Paralithodes camtschaticus) fishery is one of the largest crab fisheries in Alaska. Summer crab distributions have been well documented by decades of bottom trawl surveys. However, crab movement and distribution are poorly understood outside the summer survey period, which creates several management challenges. One important component of fishery management is the existence of no-trawl zones, which are intended to protect crab from bottom trawl fisheries. However, it is difficult to evaluate the placement of no-trawl zones, because most crab bycatch occurs in trawl fisheries during winter when crab distributions are unknown. Daily fishing logs, kept by skippers in the red king crab fleet since 2005, contain detailed information on the spatial distribution of catch and effort of legal sized male crab during the autumn crab fishery. However, data contained in these hand-written logbooks have not been readily accessible. We digitized daily fishing logs from 2005 to 2016 and used spatial information on catch and effort to infer geographic distributions of legal sized male king crab during the crab fishing season. Changes in distribution were tracked across this 12-yr period and comparisons were made between warm and cold temperature regimes. In warm years (2005, 2014–2016), crab aggregated in the center of Bristol Bay, Alaska, while in cold years (2007–2013) they were closer to the Alaska Peninsula. The majority of crab were caught in no-trawl areas (63.4% on average), but variations occurred among years and with temperature regime (40.0–86.8% in no-trawl zones). As temperatures continue to shift in the Bering Sea, it will be important to continue monitoring crab distributions outside the summer survey period.

Identifying Priority Conservation Areas of Largehead Hairtail (Trichiurus japonicus) Nursery Grounds in the East China Sea

“…In this way, the spatial distribution of nursery grounds can be more flexibly compared under the same scale, making it possible to distinguish whether there are unique spatial processes or whether the spatial structure has changed over time. Compared to the geostatistical aggregation curve (Colloca et al, 2009;Tamdrari et al, 2010) or the Getis-Ord hotspot analysis (Colloca et al, 2015;Zacher et al, 2018;Milisenda et al, 2021), the suitability index analysis does not require complex calculation but lacks statistical interpretations and objectivity in the hotspot classification criteria. In this study, since the spatial distribution pattern of juvenile largehead hairtail was inter-annually stable with slight variations in the southern part of the ECS, the persistence index could be used for nursery grounds identification.…”

Transcriptomic response to decreased pH in adult, larval and juvenile red king crab, Paralithodes camtschaticus, and interactive effects of pH and temperature on juveniles

“…The red king crab ( Paralithodes camtschaticus ) support economically and socially valuable fisheries in Alaska, USA (Stevens, 2014), many of which crashed in the early 1980s (Dew & McConnaughey, 2005; Bechtol & Kruse, 2009), and have been sustained at low levels since then (Stevens, 2014). Reasons for the fishery collapses are largely unknown but are thought to be due to overfishing (Bechtol & Kruse, 2009), shifts in ocean temperatures (Loher & Armstrong, 2005) that shift crab distributions (Zacher et al ., 2018), and increased abundance of fish that prey upon juvenile crabs (Bechtol & Kruse, 2010) and otherwise negatively impact recruitment (Zheng & Kruse, 2000), behaviour (Daly et al ., 2009) and survival of early life stages, especially glaucothoes (Stevens, 2003). While most red king crab fishing areas have been closed for decades, catch management has supported sustainable Bristol Bay red king crab fisheries in recent years, albeit at a lower level (Siddeek, 2003; Siddeek & Zheng, 2007).…”