Impacts of trophy collection and commercial fisheries on sawfishes in Queensland, Australia

Abstract

Globally, populations of sawfishes (Batoidea: Pristidae) have declined due to directed fishing and bycatch. Before international trade protection, sawfish rostra were often collected as trophies, and sawfish fins could fetch some of the highest prices in the shark fin trade. Australia is now considered a global stronghold for 4 out of 5 species. The present study analyses data of 723 sawfish rostra from all 4 Australian species that were caught in Queensland over the last 100 years. The majority of rostra (92.2%) originated from gillnet captures. Morphometric data from rostra were used to calculate sawfish total lengths and ages at mortality using published ratios. Rostra were split into the mass retention subgroup (n = 569), which originated from ≤5 active commercial inshore gillnet fishers with known large geographic origin regions and decades of origin, and the small-scale retention subgroup (n = 154), for which individual years and locations are known. Across all regions of Queensland, species composition changed significantly before and after the year 2000. After 2000, Anoxypristis cuspidata became the dominant species on the east coast. Large adult Pristis zijsron were present across Queensland before 2000 and numbers declined after this. The commercial gillnet industry likely impacts all life history stages of sawfishes. Since 2002, it has become compulsory for Queensland’s commercial fishers to report interactions with sawfishes in SOCI (Species of Conservation Interest) logbooks. Comparison of rostra from gillnet captures with logbook data indicates that underreporting is higher than previously assumed.

Kinship assessment and insights into reproductive behaviour of the Critically Endangered green sawfish Pristis zijsron in Western Australia

“…In the absence of detailed (Harry et al, 2024). The proportion of individuals that were released alive is unclear (Harry et al, 2024); however, data from Queensland indicates that sexually mature P. zijsron comprise the majority of mortalities related to trawl fisheries (Wueringer et al, 2023). In the absence of contemporary adult recruitment and fishery mortality information for P. zijsron in the southern Pilbara region, a precautionary approach should be adopted for conservation planning, such as assuming at least a moderate proportion of to result in inbreeding depression requires further investigation.…”

Historical specimens and photographs reveal long‐term changes in Smalltooth Sawfish (Pristis pectinata) age class distribution and average size during U.S. population decline

“…Because captures of P. pectinata were notable throughout their historical range, they were often photographed and their rostra retained as valuable trophies, curios, and cultural items (Fowler et al, 2005; McDavitt, 2006; Robillard & Séret, 2006; Dulvy et al, 2016). Data from these non‐traditional sources have rarely been formally evaluated for P. pectinata (see Faria et al, 2013; Waters et al, 2014) or other sawfishes (see Wueringer et al, 2023), but present an opportunity to fill gaps in contemporary research and support long‐term studies (Byler, 2017; Seitz & Hoover, 2017). There is a particular need for these data because P. pectinata has been negatively affected by habitat loss and mortalities in commercial, recreational, and small‐scale fisheries (Dulvy et al, 2016), ultimately causing a dramatic decline and range restriction (~20% of its historical global range; Dulvy et al, 2016).…”