Assessing the effectiveness of size limits and escape gaps as management tools in a commercial rock lobster (Jasus edwardsii) fishery

A Linnane, Shane Stephen Penny, M Hoare, P Hawthorne

    Research output: Contribution to journalArticleResearchpeer-review

    Abstract

    Minimum legal sizes (MLSs) and escape gaps are two commonly used management tools within commercial lobster fisheries. This study examined their effectiveness within the spatially expansive (~207,000km2) Northern Zone rock lobster (Jasus edwardsii) fishery of South Australia. Firstly, spatially explicit estimates of size of maturity (SOM) and relative reproductive potential were estimated to examine if the current minimum legal size of 105mm carapace length (CL) was appropriate. Size of maturity ranged from 105 to 118mm CL with 90% of reproductive potential coming from size classes above 105mm CL. SOM generally tended to increase from east to west and indicated that while the current MLS of 105mm CL may be appropriate for Marine Fishing Areas (MFAs) in the eastern part of the fishery, a higher MLS (>110mm CL) should be considered for MFAs in the western region of the zone. As size of maturity is age, rather than size dependent, these results may reflect differences in growth rates and highlight the importance of considering spatial variation in reproductive characteristics when applying size limits to lobster resources. Escape gap effectiveness was examined by estimating catch rates of undersized lobsters and commonly caught bycatch species, before and after mandatory introduction in 2003. After 2003, catch rates of undersized lobsters decreased by >60% while blue-throat wrasse (Notolabrus tetricus) and leatherjacket species (Meuschenia hippocrepis and Meuschenia australis) decreased by >50%. The findings have implications for the Southern Zone of South Australia where fishing effort is substantially higher but where escape gaps are not mandatory. 
    Original languageEnglish
    Pages (from-to)1-7
    Number of pages7
    JournalFisheries Research
    Volume111
    Issue number1-2
    DOIs
    Publication statusPublished - Sep 2011

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    Jasus edwardsii
    lobster
    lobsters
    rocks
    fishery
    fisheries
    rock
    South Australia
    Hippocrepis
    lobster fisheries
    Labridae
    throat
    reproductive potential
    bycatch
    spatial variation
    fishing
    lobster fishery
    fishing effort

    Cite this

    Linnane, A ; Penny, Shane Stephen ; Hoare, M ; Hawthorne, P. / Assessing the effectiveness of size limits and escape gaps as management tools in a commercial rock lobster (Jasus edwardsii) fishery. In: Fisheries Research. 2011 ; Vol. 111, No. 1-2. pp. 1-7.
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    abstract = "Minimum legal sizes (MLSs) and escape gaps are two commonly used management tools within commercial lobster fisheries. This study examined their effectiveness within the spatially expansive (~207,000km2) Northern Zone rock lobster (Jasus edwardsii) fishery of South Australia. Firstly, spatially explicit estimates of size of maturity (SOM) and relative reproductive potential were estimated to examine if the current minimum legal size of 105mm carapace length (CL) was appropriate. Size of maturity ranged from 105 to 118mm CL with 90{\%} of reproductive potential coming from size classes above 105mm CL. SOM generally tended to increase from east to west and indicated that while the current MLS of 105mm CL may be appropriate for Marine Fishing Areas (MFAs) in the eastern part of the fishery, a higher MLS (>110mm CL) should be considered for MFAs in the western region of the zone. As size of maturity is age, rather than size dependent, these results may reflect differences in growth rates and highlight the importance of considering spatial variation in reproductive characteristics when applying size limits to lobster resources. Escape gap effectiveness was examined by estimating catch rates of undersized lobsters and commonly caught bycatch species, before and after mandatory introduction in 2003. After 2003, catch rates of undersized lobsters decreased by >60{\%} while blue-throat wrasse (Notolabrus tetricus) and leatherjacket species (Meuschenia hippocrepis and Meuschenia australis) decreased by >50{\%}. The findings have implications for the Southern Zone of South Australia where fishing effort is substantially higher but where escape gaps are not mandatory. ",
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    Assessing the effectiveness of size limits and escape gaps as management tools in a commercial rock lobster (Jasus edwardsii) fishery. / Linnane, A; Penny, Shane Stephen; Hoare, M; Hawthorne, P.

    In: Fisheries Research, Vol. 111, No. 1-2, 09.2011, p. 1-7.

    Research output: Contribution to journalArticleResearchpeer-review

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    T1 - Assessing the effectiveness of size limits and escape gaps as management tools in a commercial rock lobster (Jasus edwardsii) fishery

    AU - Linnane, A

    AU - Penny, Shane Stephen

    AU - Hoare, M

    AU - Hawthorne, P

    PY - 2011/9

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    N2 - Minimum legal sizes (MLSs) and escape gaps are two commonly used management tools within commercial lobster fisheries. This study examined their effectiveness within the spatially expansive (~207,000km2) Northern Zone rock lobster (Jasus edwardsii) fishery of South Australia. Firstly, spatially explicit estimates of size of maturity (SOM) and relative reproductive potential were estimated to examine if the current minimum legal size of 105mm carapace length (CL) was appropriate. Size of maturity ranged from 105 to 118mm CL with 90% of reproductive potential coming from size classes above 105mm CL. SOM generally tended to increase from east to west and indicated that while the current MLS of 105mm CL may be appropriate for Marine Fishing Areas (MFAs) in the eastern part of the fishery, a higher MLS (>110mm CL) should be considered for MFAs in the western region of the zone. As size of maturity is age, rather than size dependent, these results may reflect differences in growth rates and highlight the importance of considering spatial variation in reproductive characteristics when applying size limits to lobster resources. Escape gap effectiveness was examined by estimating catch rates of undersized lobsters and commonly caught bycatch species, before and after mandatory introduction in 2003. After 2003, catch rates of undersized lobsters decreased by >60% while blue-throat wrasse (Notolabrus tetricus) and leatherjacket species (Meuschenia hippocrepis and Meuschenia australis) decreased by >50%. The findings have implications for the Southern Zone of South Australia where fishing effort is substantially higher but where escape gaps are not mandatory. 

    AB - Minimum legal sizes (MLSs) and escape gaps are two commonly used management tools within commercial lobster fisheries. This study examined their effectiveness within the spatially expansive (~207,000km2) Northern Zone rock lobster (Jasus edwardsii) fishery of South Australia. Firstly, spatially explicit estimates of size of maturity (SOM) and relative reproductive potential were estimated to examine if the current minimum legal size of 105mm carapace length (CL) was appropriate. Size of maturity ranged from 105 to 118mm CL with 90% of reproductive potential coming from size classes above 105mm CL. SOM generally tended to increase from east to west and indicated that while the current MLS of 105mm CL may be appropriate for Marine Fishing Areas (MFAs) in the eastern part of the fishery, a higher MLS (>110mm CL) should be considered for MFAs in the western region of the zone. As size of maturity is age, rather than size dependent, these results may reflect differences in growth rates and highlight the importance of considering spatial variation in reproductive characteristics when applying size limits to lobster resources. Escape gap effectiveness was examined by estimating catch rates of undersized lobsters and commonly caught bycatch species, before and after mandatory introduction in 2003. After 2003, catch rates of undersized lobsters decreased by >60% while blue-throat wrasse (Notolabrus tetricus) and leatherjacket species (Meuschenia hippocrepis and Meuschenia australis) decreased by >50%. The findings have implications for the Southern Zone of South Australia where fishing effort is substantially higher but where escape gaps are not mandatory. 

    KW - Hippocrepis

    KW - Jasus edwardsii

    KW - lobster

    KW - Meuschenia

    KW - Meuschenia australis

    KW - Notolabrus tetricus

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    U2 - 10.1016/j.fishres.2011.06.006

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    JF - Fisheries Research

    SN - 0165-7836

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