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Long-term decline in northern pike (Esox lucius L.) populations in the Baltic Sea revealed by recreational angling data

Bergström, Ulf and Larsson, Stefan and Erlandsson, Mårten and Ovegård, Maria and Ragnarsson Stabo, Henrik and Östman, Örjan and Sundblad, Göran (2022). Long-term decline in northern pike (Esox lucius L.) populations in the Baltic Sea revealed by recreational angling data. Fisheries Research. 251 , 106307
[Research article]

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Abstract

In the Baltic Sea, the large predatory fish northern pike (Esox lucius L.) is important for both recreational fisheries and ecosystem functioning. As existing fishery-independent surveys do not adequately monitor pike populations, a general lack of knowledge on population status and trends poses challenges for management. Here we use recreational angling data as an alternative method to describe pike population development along the Swedish Baltic Sea coast from 1938 onwards and assess the change over time in potential mortality factors by estimating harvest by fisheries and consumption by large predators. Data from a Swedish national register on trophy-sized pike (>12 kg) showed that numbers and maximum sizes peaked in 1990-1995, after which declines in both metrics are evident. In logbooks from a sport fishing club in the Stockholm archipelago, a simultaneous decrease in maximum sizes of pike was observed, together with a decrease in the total number of pike caught per fishing day. Jointly, these data indicate a decline in the abundance of large pike since around 1990. While commercial pike fisheries in the Baltic Sea have decreased continuously since the 1950s, recreational fishing increased after 1985, when Swedish coastal waters were made open access to anglers. The declines in large pike starting in the 1990s could, thus, have been driven by an increase in mortality from recreational fisheries, which at the time primarily practiced catch and kill. Since the 2000s, bag and slot length limits, spawning closures, and a general increase in catch-and-release fishing has reduced the landings of pike in recreational fisheries. Despite these fisheries regulations and higher release rates the decline in catches of large pike has continued, indicating an effect of other mortality factors. The strong growth of grey seal (Halichoerus grypus) and great cormorant (Phalacrocorax carbo sinensis) populations suggest that predation pressure on pike has increased over time. In the Stockholm archipelago these two predators were estimated to remove 5-18 times (range based on different diet composition estimates) more pike biomass than total fisheries landings in 2014-2017. To improve the situation for northern pike in the Baltic Sea managers need to consider both fisheries restrictions and measures to decrease predation pressure and increase recruitment. Catch data from recreational fisheries may be used to evaluate such management efforts by providing information on the population development of this keystone species.

Authors/Creators:Bergström, Ulf and Larsson, Stefan and Erlandsson, Mårten and Ovegård, Maria and Ragnarsson Stabo, Henrik and Östman, Örjan and Sundblad, Göran
Title:Long-term decline in northern pike (Esox lucius L.) populations in the Baltic Sea revealed by recreational angling data
Series Name/Journal:Fisheries Research
Year of publishing :2022
Volume:251
Article number:106307
Number of Pages:10
Publisher:ELSEVIER
Associated Programs and Other Stakeholders:SLU - Environmental assessment > Programme Coastal and sea areas
SLU - Environmental assessment > Programme Lakes and watercourses
ISSN:0165-7836
Language:English
Publication Type:Research article
Article category:Scientific peer reviewed
Version:Published version
Copyright:Creative Commons: Attribution 4.0
Full Text Status:Public
Subjects:(A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Fish and Aquacultural Science
Keywords:Angling, Sport fishing, Logbook data, Large predatory fish, Marine mammals, Fish-eating birds
URN:NBN:urn:nbn:se:slu:epsilon-p-118017
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-118017
Additional ID:
Type of IDID
DOI10.1016/j.fishres.2022.106307
Web of Science (WoS)000805456200012
ID Code:28600
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Aquatic Resources
Deposited By: SLUpub Connector
Deposited On:26 Aug 2022 11:24
Metadata Last Modified:26 Aug 2022 11:31

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