Faster or slower: has growth of eastern Baltic cod changed?

Karin Hüssy*, Margit Eero, Krzysztof Radtke

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

Recent environmental changes have influenced the ecology and biology of eastern Baltic cod. Declining somatic condition, maturation at smaller size and restricted size distribution of the population suggest that growth rates have decreased between the early 2000s and the 2010s. Extensive age estimation problems have until now precluded testing of this hypothesis. This study presents evidence for a decrease in somatic growth rate of Baltic cod.
Temporal patterns of growth, condition and maturation were analysed based on two complementary analyses: length frequency mode progression derived from DATRAS bottom trawl survey data and known-age samples, where size at age was back-calculated from daily otolith growth patterns. In the known-age samples, growth was positively related to somatic condition at capture with maturity dependent differences. Immature individuals had experienced significantly lower growth and were in lower condition at capture than mature
individuals. Growth rates in the known-age samples were estimated at 9.5, 7.8 and 5.7 cm per year for age classes 1, 2 and 3 respectively. Growth between age 2 and 3 decreased significantly from 8.8 cm in the 1997 year class to 7.6 cm in the 2010 year class. While the 2001 and 2004 known-age samples were representative for the population, the 2013 sample was biased towards individuals with a higher condition and growth. Complementary length
frequency analysis following the length mode of fish from age 2 to age 3 confirmed growth estimates from the early 2000s, while suggesting a 37.5% lower growth in 2013 compared with 2005
Original languageEnglish
JournalMarine Biology Research
Volume14
Issue number6
Pages (from-to)598-606
ISSN1745-1000
DOIs
Publication statusPublished - 2018

Keywords

  • Back-calculation
  • Baltic cod
  • Growth
  • Length frequency
  • Maturation
  • Otolith

Cite this

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title = "Faster or slower: has growth of eastern Baltic cod changed?",
abstract = "Recent environmental changes have influenced the ecology and biology of eastern Baltic cod. Declining somatic condition, maturation at smaller size and restricted size distribution of the population suggest that growth rates have decreased between the early 2000s and the 2010s. Extensive age estimation problems have until now precluded testing of this hypothesis. This study presents evidence for a decrease in somatic growth rate of Baltic cod.Temporal patterns of growth, condition and maturation were analysed based on two complementary analyses: length frequency mode progression derived from DATRAS bottom trawl survey data and known-age samples, where size at age was back-calculated from daily otolith growth patterns. In the known-age samples, growth was positively related to somatic condition at capture with maturity dependent differences. Immature individuals had experienced significantly lower growth and were in lower condition at capture than matureindividuals. Growth rates in the known-age samples were estimated at 9.5, 7.8 and 5.7 cm per year for age classes 1, 2 and 3 respectively. Growth between age 2 and 3 decreased significantly from 8.8 cm in the 1997 year class to 7.6 cm in the 2010 year class. While the 2001 and 2004 known-age samples were representative for the population, the 2013 sample was biased towards individuals with a higher condition and growth. Complementary lengthfrequency analysis following the length mode of fish from age 2 to age 3 confirmed growth estimates from the early 2000s, while suggesting a 37.5{\%} lower growth in 2013 compared with 2005",
keywords = "Back-calculation, Baltic cod, Growth, Length frequency, Maturation, Otolith",
author = "Karin H{\"u}ssy and Margit Eero and Krzysztof Radtke",
year = "2018",
doi = "10.1080/17451000.2018.1502446",
language = "English",
volume = "14",
pages = "598--606",
journal = "Marine Biology Research",
issn = "1745-1000",
publisher = "CRC Press/Balkema",
number = "6",

}

Faster or slower: has growth of eastern Baltic cod changed? / Hüssy, Karin; Eero, Margit; Radtke, Krzysztof.

In: Marine Biology Research, Vol. 14, No. 6, 2018, p. 598-606.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Faster or slower: has growth of eastern Baltic cod changed?

AU - Hüssy, Karin

AU - Eero, Margit

AU - Radtke, Krzysztof

PY - 2018

Y1 - 2018

N2 - Recent environmental changes have influenced the ecology and biology of eastern Baltic cod. Declining somatic condition, maturation at smaller size and restricted size distribution of the population suggest that growth rates have decreased between the early 2000s and the 2010s. Extensive age estimation problems have until now precluded testing of this hypothesis. This study presents evidence for a decrease in somatic growth rate of Baltic cod.Temporal patterns of growth, condition and maturation were analysed based on two complementary analyses: length frequency mode progression derived from DATRAS bottom trawl survey data and known-age samples, where size at age was back-calculated from daily otolith growth patterns. In the known-age samples, growth was positively related to somatic condition at capture with maturity dependent differences. Immature individuals had experienced significantly lower growth and were in lower condition at capture than matureindividuals. Growth rates in the known-age samples were estimated at 9.5, 7.8 and 5.7 cm per year for age classes 1, 2 and 3 respectively. Growth between age 2 and 3 decreased significantly from 8.8 cm in the 1997 year class to 7.6 cm in the 2010 year class. While the 2001 and 2004 known-age samples were representative for the population, the 2013 sample was biased towards individuals with a higher condition and growth. Complementary lengthfrequency analysis following the length mode of fish from age 2 to age 3 confirmed growth estimates from the early 2000s, while suggesting a 37.5% lower growth in 2013 compared with 2005

AB - Recent environmental changes have influenced the ecology and biology of eastern Baltic cod. Declining somatic condition, maturation at smaller size and restricted size distribution of the population suggest that growth rates have decreased between the early 2000s and the 2010s. Extensive age estimation problems have until now precluded testing of this hypothesis. This study presents evidence for a decrease in somatic growth rate of Baltic cod.Temporal patterns of growth, condition and maturation were analysed based on two complementary analyses: length frequency mode progression derived from DATRAS bottom trawl survey data and known-age samples, where size at age was back-calculated from daily otolith growth patterns. In the known-age samples, growth was positively related to somatic condition at capture with maturity dependent differences. Immature individuals had experienced significantly lower growth and were in lower condition at capture than matureindividuals. Growth rates in the known-age samples were estimated at 9.5, 7.8 and 5.7 cm per year for age classes 1, 2 and 3 respectively. Growth between age 2 and 3 decreased significantly from 8.8 cm in the 1997 year class to 7.6 cm in the 2010 year class. While the 2001 and 2004 known-age samples were representative for the population, the 2013 sample was biased towards individuals with a higher condition and growth. Complementary lengthfrequency analysis following the length mode of fish from age 2 to age 3 confirmed growth estimates from the early 2000s, while suggesting a 37.5% lower growth in 2013 compared with 2005

KW - Back-calculation

KW - Baltic cod

KW - Growth

KW - Length frequency

KW - Maturation

KW - Otolith

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DO - 10.1080/17451000.2018.1502446

M3 - Journal article

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EP - 606

JO - Marine Biology Research

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