@article{fdi:010037869,
  title = {{A}nchovy ({E}ngraulis ringens) and sardine ({S}ardinops sagax) spatial dynamics and aggregation patterns in the {H}umboldt {C}urrent ecosystem, {P}eru, from 1983-2003},
  author = {{G}uti{\'e}rrez, {M}. and {S}wartzman, {G}. and {B}ertrand, {A}rnaud and {B}ertrand, {S}ophie},
  editor = {},
  language = {{ENG}},
  abstract = {{T}hree indexes of spatial aggregation are developed and used to examine the aggregation pattern of sardine ({S}ardinops sagax) and anchovy ({E}ngraulis ringens) in the {P}eruvian {H}umboldt {C}urrent {S}ystem, determined from 36 acoustic surveys conducted from 1983 through 2003 by the {P}eruvian {M}arine {I}nstitute ({IMARPE}). {E}ach index assesses a different aspect of aggregation: the concentration, the percent occupancy of space and the clustering of high-fish abundance. {B}oth time-series correlation and tree-based clustering-regression method, classification and regression trees ({CART}), were used to relate each of the indexes to environmental variables (season, temperature anomaly and year). {A}dditionally, a measure of onshore-offshore distribution, the average distance from the coast, and abundance variables (the average acoustic backscatter per occupied sampling unit, and the acoustically estimated total abundance of sardine and anchovy from {IMARPE}) were related to environmental factors by using {CART}. {W}e show that the 1983-2003 time series can be divided into three different periods: with shifts in 1992 and in 1997-98. {S}ardine and anchovy showed large differences in both abundance and aggregation among these periods. {A}lthough upwelling ecosystems support dramatic and sudden changes in environmental conditions, fish responses are sometimes smoother than usually suggested and there are transition periods with concomitant high biomasses of anchovy and sardine, but with different spatial aggregation patterns. {O}bserved relationships between environmental proxies and aggregation patterns support the habitat-based hypothesis that environmentally mediated alterations in range lead to population changes.},
  keywords = {anchovy ; {E}l {N}ino {S}outhern {O}scillation ; pelagic fish spatial aggregation ; {P}eru {H}umboldt {C}urrent {S}ystem ; sardine ; time series},
  booktitle = {},
  journal = {{F}isheries {O}ceanography},
  volume = {16},
  numero = {2},
  pages = {155--168},
  ISSN = {1054-6006},
  year = {2007},
  DOI = {10.1111/j.1365-2419.2006.00422.x},
  URL = {https://www.documentation.ird.fr/hor/fdi:010037869},
}