Accurate spatial ecology of endangered Saimaa ringed seals as a base for fishing closure determination

(Poster)

Marja Niemi
marja.niemi@uef.fi

University of Eastern Finland Department of Environmental and Biological Sciences P.O. Box 111, FI-80101 Joensuu, Finland, Finland
,
Miina Auttila
Metsähallitus, Parks & Wildlife Finland, FI-57130 Savonlinna, Finland, Finland
,
Tero Sipilä
Metsähallitus, Parks & Wildlife Finland, FI-57130 Savonlinna, Finland, Finland
,
Mervi Kunnasranta
University of Eastern Finland Department of Environmental and Biological Sciences P.O. Box 111, FI-80101 Joensuu, Finland and Natural Resources Institute Finland (Luke), FI-80100 Joensuu, Finland, Finland

DOI: 10.17011/conference/eccb2018/107535

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Saimaa ringed seal (Phoca hispida saimensis) is an endangered subspecies living landlocked in Lake Saimaa, southeastern Finland. One of the major threats of this small population (ca 370 seals) is by-catch due to mainly recreational gill net fishing. For mitigating by-catch mortality varied fishing closures and restrictions have been established in the lake over time. The fishing restrictions cover year round ban of the most dangerous fishing methods and springtime (15.4.-30.6.) gill net ban to protect especially the pups. In this study, we describe the usage of accurate spatial ecology data of the Saimaa ringed seals as a base for conservation measures. Telemetry tracking data of both; juveniles and adults (N= 41) together with the lair and haul out locations were used to determine the key distribution area for conservation measures. Radius of average home range (5.2 km) is buffered over known lair and haul out sites, to create overall occurrence area of the seals. The distribution area usage of the seals indicate that the seals occur almost all of lake surface area. This method approach was already utilized by government Decree (259/2016), and now closures are covering spatially ca. 60% of the lake surface area (4 400 km2). However, bycatch mortality still exists, which indicate that closures are inadequate and whole distribution area would need more fishing closures. Furthermore, the temporal gill net ban is underestimated as nowadays the by-catch mortality takes place outside the temporal ban.

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INTRO:
The Saaima ringed seal is an endangered species of conservation concern, and although measures have been taken to minimize mortality due to fishing by-catch, it is still a problem. By mapping the distribution area of the seals, it is shown that they occur over almost all of the surface of the lake that they inhabit. The authors suggest that extended fishing closures and gill netting ban is needed to safeguard the Saaima ringed seal.
MERITS:
The study provides a good example of how the spatial ecology approach can be used as a base for conservation and management planning. It also shows the importance to rewiew the effectiveness of current conservation and management plans and measures. The abstract is written clearly and is easy to follow and understand.

CRITIQUE:
The structure of the abstract could benefit if some parts of the two last sentences were moved higher up; by describing the problem, it would be more clear why you mapped the spatial distribution of the seals. It is also interesting to know the magnitude of the by-catch mortality occurring, are there any estimations of that?
DISCUSSION:
This study shows that current conservation policies intended to safeguard a small population of an endemic seal subspecies are not as effective as they should be. Thus, the study is very interesting and important as it identifies the need to continuously rewiew the effectiveness of conservation and management plans and policies.

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INTRO:
The study seeks to know more about the distribution area of usage of the Saimaa ringed seal within the Lake Saimaa. This seal is an endemism (subspecies) occurring only in the Lake Saimma, Finland. Despite being endangered and protected, there is still by catch mortality of individuals due to inappropriate estimation of species distribution/usage of the lake and inefficient temporal gill net bans.
MERITS:
The fact that the target species is endemic and endangered gives this study a high value/importance. The study can potentially contribute to improve management plans for the species (set up new ban areas).
CRITIQUE:
The title mentions 'acurate spatial ecology', however, from the abstract I understand the authors only applied a buffer radius (average home range for the species) from the collected telemetry data to identify areas of species usage within the lake. I also understand, the government has also used this method to identify areas of gill net bans but there is still mortality. Do the authors have used or considered other spatial ecology tools to identify the preferred locations for the species given for example, abundance of food resources? human disturbance? Have they considered using species distribution models to identify preferred conditions for the species within the lake? It would be interesting to hear about this (also considering the study seeks to improve what is already done by the government).
DISCUSSION:
It would be very interesting to know whether the results of the study will be applied by the government to improve conservation plans for the species (or how the authors will communicate this results to the government).