Premium
Production biology of the upland bully Philypnodon breviceps Stokell in a small New Zealand lake
Author(s) -
Staples D. J.
Publication year - 1975
Publication title -
journal of fish biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.672
H-Index - 115
eISSN - 1095-8649
pISSN - 0022-1112
DOI - 10.1111/j.1095-8649.1975.tb04575.x
Subject(s) - biology , population , biomass (ecology) , seasonality , fish <actinopterygii> , zoology , body weight , age groups , ecology , toxicology , fishery , demography , sociology , endocrinology
Estimates of production, food consumption and efficiency of food utilization for a population of the upland bully, Philypnodon breviceps Stokell, in Small Spectacles (the smaller of two lakes known as Spectacles Lakes) are given for the period February 1969 to March 1970. Length: weight relations were similar among age groups within any one month but a seasonal variation in the ‘condition’ offish, as well as in calorific content of body tissue, was recorded. The mean population biomass was estimated as 21.98 g/m 2 (21.85 kcal/m 2 ) over the study period; maximum biomass of younger age groups occurred during the late summer but little seasonal change occurred in older groups. Total annual production was 39.78 ±8.25 g/m 2 (39.55 kcal/m 2 ), but this estimate did not include any fish in their first 1.5 months of life because of the lack of recruitment during the 1969 breeding season. Approximately 70% of production occurred during three months in late spring and summer, and 97% resulted from the two youngest age groups. In fish over one year old, male production doubled that of females, a difference which could be attributed to the greater number and faster growth of male fish. Production due to sexual products amounted to less than 1% of the total production. Annual food consumption was approximately 302.8 g/m 2 (249.7 kcal/m 2 ) and the gross efficiency of food utilization was in the order of 16%. Efficiency was similar between sexes of the same age group; faster growth and production of males, therefore, resulted from a greater food consumption rather than a difference in utilization of food. Efficiency was highest during spring and summer and, for most of the year, decreased with age. Efficiency was low in autumn when, although food consumption was relatively high, little production resulted. These seasonal and age differences are discussed with respect to Paloheimo & Dickie's K ‐line model.