The niche of shrimp stocks (Xiphopenaeus kroyeri Heller, 1862) from southeastern Brazil: a stable isotope approach

The penaeid shrimp Xiphopenaeus kroyeri is the second most important species of crustacean in Brazilian fisheries. Stable isotopes of carbon and nitrogen are chemical proxies to provide quantitative information about the consumer isotopic niche, which is associated with its feeding ecology and ecological niche in the environment. This study evaluated the niche dimensions of X. kroyeri from different stocks through stable isotopes determinations. Shrimps were sampled in four fishing areas from southeastern Brazil (Vitória and Anchieta, in Espírito Santo State, and Atafona and Farol de São Tomé, in Rio de Janeiro State). The stable isotopes of carbon and nitrogen were determined in the abdominal muscle. Quantitative metrics of the isotopic niche estimated the trophic diversity and trophic redundancy among stocks. Shrimp stocks from Espírito Santo State had highest trophic diversity, indicating greater variety of food sources and wider utilization of the available food sources. The shrimps from Rio de Janeiro State had highest trophic redundancy, revealing a more homogeneous dietary pattern. The isotopic niche approach allowed the discrimination of X. kroyeri stocks distributed in southeastern Brazil, and the results will be helpful to assist fisheries management.