Age, growth and reproduction of non-native largemouth bass Micropterus salmoides (Lacépède, 1802) populations in two temperate African impoundments
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This study aims to improve the understanding of the establishment success of Micropterus salmoides by assessing growth, maturity and reproductive seasonality of two populations from the temperate region in South Africa. Results are compared to those from other populations to test previously proposed hypotheses that the (i) extent of the spawning season, (ii) longevity, and (iii) growth performance are environmentally temperature dependent. Micropterus salmoides were sampled monthly between March 2010 and March 2012 from Wriggleswade and Mankazana impoundments using either angling or multi-meshed (35, 45, 47, 57, 65, 73, 77, 93, 106, 118, 150 and 153 mm) multifilament gillnet fleets, and a 1 m seine net. The assessed populations in South Africa performed as expected compared to other introduced populations. Age at maturity (1.3–2 years) and length at maturity (232–254 mm FL) were similar to other temperate populations. A well-defined, spring spawning season conformed to findings in other temperate populations. Using sectioned sagittal otoliths I was shown that fish were long-lived (14 years). Growth rates differed significantly between the two assessed populations but both were slower growing than tropical and subtropical introduced populations. Growth performance (Φ′: 2.77–2.99) was similar to other temperate populations. These results indicate that the biology of introduced M. salmoides populations in South Africa is comparable to those of other temperate populations and supports the environmental temperature-dependent hypothesis.
- RESEARCH: Weyl, O