Time and area management refers to the temporary closure of fisheries in response to a high presence of sensitive marine species, seasonal breeding grounds, or important migration routes. These closures are temporally and spatially targeted, due to the variable nature of bycatch incidences. Furthermore, ‘blanket’ closures of fisheries are rarely possible due to the social and economic repercussions on fishermen. As monthly peaks in bycatch rates can change each year, adaptive management strategies allow the time or area closure to be modified from year to year.
There are various challenges associated with this mitigation strategy. Primarily, fishermen are often opposed to being excluded from valuable fishing grounds due to the inevitable financial loss. Clear communication between researchers, regulators and fishermen is vital for fishermen’s cooperation. Time-area closures can also result in heightened fishing activity just outside of the closure, paradoxically ‘shifting’ the risk of entanglement and bycatch to these areas.
Overall, this technique has been found to be very effective at reducing the bycatch and mortality of seabirds and cetaceans, with potential for seals, sharks and rays as well.
Due to the mobile nature of seabirds, their prey, and fisheries, predicting the appropriate time and area closures can be difficult. This is illustrated by a bycatch event in St Ives Bay, Cornwall in a set gillnet fishery that caught 163 birds, triggering a local bye-law which closed the fishery for 21 days. However, subsequent to this, a large number of birds were caught in a neighbouring region outside the bye-law area as the target focus of the fishery moved (E. Dunn, RSPB, pers. obs.).
Following a number of Right Atlantic Whale deaths in the Southern Gulf of St. Lawrence in 2017, Fisheries and Oceans Canada have implemented time-area closures in the Gulf’s snow crab fishery, to reduce the risk of entanglement. A Right Whale sighting will trigger the exclusion of fishing activity from the area where the whale was sighted, staying in effect for a minimum of 15 days. Such time-area closures are used throughout the Maritime provinces. However, a 2023 modelling exercise of management strategies for the California Dungeness crab trap fishery indicated that reducing the amount of gear used would be more effective in reducing the rate of entanglement of humpback whales, in comparison to reactive closures of certain areas of the fishery.
Modelling has been undertaken for fisheries in Atlantic Canada, which pose a threat to vulnerable species of skate, to optimise the use of space-based management for mitigating bycatch. The results indicated that when area closures to mitigate the bycatch risk to skates are precisely placed, there can be relatively minimal economic costs for fishers, with 10% of landed catch weight being displaced in exchange for a 50% reduction in skate bycatch risk.
Whilst this technique may be effective and is simple to implement, it can have negative social and economic impacts, for example by affecting target catch. Extensive knowledge of local conditions, along with regular monitoring and enforcement, are essential for this technique to work.
Interested in how this and other measures could mitigate bycatch in your fishery? Get in touch with us to collaborate or take part in a study.
This page was last updated on 12.10.23.