Skip to main content

Assessment of Species Catch Composition in Fisheries Posing a Risk to Biodiversity Phase 2

The estimation of bycatch of protected, endangered and threatened species (PET) in commercial fisheries and its sustainability assessment is an important consideration in the implementation of the Common Fisheries Policy, the Marine Strategy Framework directive (Descriptor 1) and the Habitats and Bird’s directives. Since 2016, the reporting of all bycatch is a requirement of the data collection framework to support this assessment (EU MAP: EU- 2016 1251). This project follows on from the assessment of species catch composition in Phase 1.

Although Ireland currently has an observer programme on commercial inshore and offshore fleet metiers, and records all bycatch, these programmes are optimised for assessment of fish catches for the Data Collection Framework (DCF). PET species are not typical in fish catches but occur sporadically but also potentially catastrophically in the case of small or localised/resident populations (i.e. potentially high but infrequent by-catch). Estimates for such zero inflated data are difficult to obtain and the resolution of this problem requires an enhanced observer programme for fleet metiers that pose the highest risk of by-catch of such species.  In 2017-2018, in consultation with other end-users, the fisheries that have been identified as posing the highest risk to bycatch and warrant an enhanced bycatch programme, are set net fisheries in the first instance. These have received additional sampling effort on a national and regional level (SW table net fishery). In 2018, additional effort has been provided to the pelagic trawl fishery catching horse mackerel.

  • This enhanced data collection could usefully be combined with sample provision to existing studies (e.g., population genetics) to augment information on the population ecology of species that are incidentally caught. High uncertainty of by-catch is one of the gaps identified in the Fisheries Natura risk assessment for seals and cetaceans (Marine Institute 2015).
  • The at sea observer programme will be used to collect bycatch data. As in Phase 1, observers will collect small tissue samples from by-caught species for laboratory analysis (i.e., skin and blubber biopsy) and collect seabird carcasses to enhance data collection. In 2019-2020, observers will be provided with small toolkits related to the collection and storage of tissue samples.
  • A co-ordinating observer will be contracted to manage the enhanced observer programme. This will include the identification and allocation of trips to observers across the different metiers, payments to observers and logging of data & sample returns. All SOPs and data management procedures for this type of work are already established in the Marine Institute. Methods will be reviewed based on the outcomes from the EASME funded project fishPi2 and the ICES workshop PETSAMP.


The project is carried out in close collaboration with the Marine Institute (Fisheries Ecosystem Advisory Services), National Parks and Wildlife Services, and its parent department, Department of Culture, Heritage and the Gaeltacht (DCHG). The post-mortem examinations of stranded cetaceans are carried out on behalf of the project partners by the Irish Whale and Dolphin Group (IWDG), Galway Mayo Institute of Technology and the Veterinary Laboratory of the Department of Agriculture, Food and the Marine (DAFM) benefitting from specimen collected under the Cetacean Strandings Scheme.


The project has a 2 year duration and runs between 2019 and 2020.

Project Outputs:
  • Screening of stranded carcasses of seals and small cetaceans: Although the observer programme observes a sample of the fisheries by-catch in real time and can provide estimates of total by-catch for different metiers if there is adequate coverage, additional information can be obtained if the cause of mortality of stranded animals is determined. Under Ireland’s ongoing Cetacean Strandings Scheme a small proportion of the annual stranding records show scientifically established external signs of fisheries by-catch, including broken bones, obvious net marks, gear entanglement or fins cleanly removed. In parallel with its at-sea observation method, the enhanced monitoring programme provides an important opportunity to subsample stranded marine mammal carcasses for evidence of by-catch interaction, if this occurs. It is aimed to use both components of the study to inform one another, improve the assessment of relevant metiers of concern and to enhance scientific and management understanding of such interactions and their risk to protected species. This project will establish contracts for the targeted recovery and post-mortem examination of a sub-sample of small cetaceans stranded around the south and west coasts of Ireland through liaison with the coordinator of the Cetacean Strandings Scheme and through international best practice in post-mortem examination (PME).​


  • Data obtained from Phase 1 and Phase 2 will be used to model the risk of bycatch to populations of different PET species.​​
  • Future sampling recommendations: Results from the enhanced by-catch monitoring programme will be reviewed in relation to end-user requirements. Recommendations on sampling methodologies and sampling effort for bycatch monitoring will be drafted to inform future data collection programmes (link to UP3) and will feed into the review of EUMAP.
  • Bycatch data will be disseminated to endusers via official data calls and in direct consultation with national and international endusers (eg DAFM, DCHG, DHPLG, ICES, DCF RCG North Atlantic ). 


Expected Benefit:
  1. Improved scientific reporting in on bycatch events of seals, small cetaceans, seabirds and rare and endangered species by fishing metier.
  2. Scientific reporting on the evidence, if any, for fisheries by-catch in the population of stranded cetaceans around the Irish coast.
  3. Training of Irish scientists in international best practice where PME of marine mammals is concerned.
  4. Contribution of key tissue samples of relevance in assessing population structure and ecology among the species by-caught in monitored metiers.
  5. Future estimates of the population level effects of by-catch on seals, small cetaceans and rare and endangered species.
  6. Recommendations and management coordination on mitigation measures to ensure compliance with EU Directives.
  7. Recommendations on sampling methodologies and sampling effort for bycatch monitoring to inform future data collection programmes under revised EUMAP (link to UP3).
  8. 8. Enhanced ability to advise on permissible by-catch levels for marine mammals.
Further Information:
Project Cost - Projected:
Project Status: