Applying global best practices for estimating unreported catches in Norwegian fisheries under a discard ban

Abstract

In addition to their role as a fisheries management tool, discard bans can be effective in improving knowledge of total catches via the requirement to land and report all catches. This shifts the focus to understanding the scale of unreported catches in fisheries, rather than only on discards. However, the presence of a discard ban can cause problems with estimation process, as it involves the observation of illegal activities, and the complex sources of unreported catches require a different approach to estimation. The Norwegian discard ban was introduced in 1987 as part of a wider suite of regulatory measures to improve exploitation patterns in commercial fisheries, but a framework for the regular estimation of unreported catches has yet to be established and operationalised. Here, we aim to identify global best practices for estimating unreported catches under a discard ban and assess their applicability to Norwegian fisheries. We approach this in three steps: (1) defining the scope of an estimation, (2) data collection, and (3) the actual procedure for estimation. We discuss how each step can affect the quality of an estimate with regards to accuracy, precision, practical limitations and whether the estimate is fit for purpose. Finally, we provide a list of recommendations for future studies and identify key knowledge gaps and limitations regarding their application to Norwegian fisheries.

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“…Information on the wider marine distribution of pink salmon comes from bycatch in commercial fisheries targeting other pelagic species reported by the Norwegian Reference Fleet (Clegg and Williams 2020) and in scientific trawl surveys such as the International Ecosystem Survey in Nordic Seas (IESNS) (Diaz Pauli et al 2023).…”

Discards of cod (Gadus morhua) in the Norwegian coastal fisheries: improving past and future estimates

“…Hook (longline and jigging) and Danish seine fisheries accounted for 34% and 8% of cod catches, respectively. However, the latter fisheries were excluded from the study as the Norwegian Reference Fleet programme prioritizes these fishing gears only for specific areas and target species (Clegg and Williams, 2020).…”

“…The participating vessels in the Norwegian Reference Fleet are selected through an open tender process and are paid for high-resolution self-sampling and recording of catches. The tender specifications (see Clegg and Williams, 2020) aim to select vessels that are representative of the wider fleet in each statistical area. If multiple vessels meet the required specifications, then the contract is awarded randomly.…”

eDNA based bycatch assessment in pelagic fish catches

“…Following the increase in public awareness on the issue of bycatch and discards in the early 2000s, increased focus has been put on identifying and estimating quantities of bycaught species 9 – 11 , and implementing rules and regulations such as the EU landing obligation 12 . Bycatch estimation is currently conducted using various approaches such as self-reporting by the fisherman via obligatory logbook documentation or through observer programs 9 , 13 . However, such methods can be biased as they rely on relatively rough visual estimates, the fisherman’s cooperation 14 , and manual species identification ease 15 .…”