全球智库信息集成服务系统(G2TT): Reaction Norms for Age and Size at Maturation: Study of the Long-Term Trend (1970-1998) for Georges Bank and Gulf of Maine Cod Stocks.

G2TT

来源类型	Monograph (IIASA Interim Report)
规范类型	报告
	Reaction Norms for Age and Size at Maturation: Study of the Long-Term Trend (1970-1998) for Georges Bank and Gulf of Maine Cod Stocks.
	Barot S; Heino M; O'Brien L; Dieckmann U
发表日期	2004
出版者	IIASA, Laxenburg, Austria: IR-04-011
出版年	2004
语种	英语
摘要	Average age and size at maturation have decreased in many commercially exploited fish stocks during the last decades. This phenomenon could be either a direct phenotypic response to some environmental variation, or the evolutionary consequence of some selective pressure. Traditionally used maturation indices, i.e., the age and size at which 50% of individuals are mature, are not appropriate to assess the causes of changes in maturation because they are influenced, in addition to maturation per se, by growth and survival. To make up for this shortcoming, we use a reaction norm based approach to disentangle evolutionary changes and phenotypic plasticity. A method is presented to estimate the reaction norm for age and size at maturation from data commonly gathered for the maturation of fisheries. This method is applied to data on Georges Bank Gulf of Maine stocks of Atlantic cod ("Gadus morhua"). The results show that maturation reaction norms in these stocks have shifted significantly downwards, resulting in a tendency to mature earlier at smaller size. These findings support the hypothesis that an evolutionary trend, probably caused by high fishing mortalities, is partially responsible for the observed decrease in age and size at maturation in these cod stocks. Two independent reasons justify this interpretation. First, there is no corresponding trend in growth that would suggest that improved feeding conditions could have facilitated maturation. Second, the results are based on maturation reaction norms, from which the known confounding effects of the growth and mortality variations are removed. Consequences of fisheries-induced evolution for the sustainability of the fisheries are discussed.
主题	Adaptive Dynamics Network (ADN)
URL	http://pure.iiasa.ac.at/id/eprint/7434/
来源智库	International Institute for Applied Systems Analysis (Austria)
资源类型	智库出版物
条目标识符	http://119.78.100.153/handle/2XGU8XDN/125360
推荐引用方式 GB/T 7714	Barot S,Heino M,O'Brien L,et al. Reaction Norms for Age and Size at Maturation: Study of the Long-Term Trend (1970-1998) for Georges Bank and Gulf of Maine Cod Stocks.. 2004.

条目包含的文件
文件名称/大小	资源类型	版本类型	开放类型	使用许可
IR-04-011.pdf（597KB）	智库出版物		限制开放	CC BY-NC-SA	浏览