Observations of male three-spined stickleback (Gasterosteus aculeatus L.) parental care were made in a salt-marsh tide pool at 3-h intervals over 24-h cycles, to determine if male behavior varied in association with diel changes in water temperature and dissolved oxygen concentration. An analysis of egg metabolism in situ revealed positive correlations between rate of egg oxygen consumption and egg age, water temperature, and dissolved oxygen levels, while there was a slight but significant negative correlative with the number of eggs per nest. We found no significant difference when we compared the proportion of time males spent fanning their nests during the day with night levels. However, nocturnal fanning bouts were significantly longer and less numerous than diurnal ones. In contrast to the rest of the 24-h cycle, the males remained inactive between fanning bouts at night, except when exposed to hypoxic conditions

A random sample of 17 threespine stickleback nests was analysed using DNA fingerprinting. DNA from the guardian male and a random subsample of 10 fry per nest was probed with pYNZ132, a human single-locus VNTR probe which detects a multilocus fingerprint pattern in sticklebacks. Band-sharing indices (BSZs, the proportion of bands shared by two individuals) between the guardian male and its fry were calculated. In 147 of a total of 170 pair-wise comparisons the BSZs varied between 0.40 and 0.77. The guardian male was thought to be the true father of all these fry (Pc0.10). For the remaining 23 fry the BSZs vaned between 0.09 and 0.34, suggesting that these fry were fathered by a different male (P<0.06). Once the paternal bands in each legitimate fry were determined, the remaining (i.e. maternal) bands among these fry were compared.Based on the BSIs obtained, the minimum number of females that spawned per nest was determined, and the maternal DNA fingerprints of the legitimate fry were traced back.In one nest five eggs of the sample had been fertilized by a sneaker, in two nests the guardian male had stolen eggs from a rival male, and in another nest one of the eggs was fertilized by a sneaker and three were stolen eggs.

No abstract

No abstract

A comparison between an anadromous and a freshwater lake population of brook charr showed that anadromous charr had a lower mean length at age 2+ and 3+, a greater longevity, a greater maximal length and a greater length and age at first maturity than the freshwater population. A biased sex ratio towards females occurred only in the anadromous population. The first 2 or 3 years in the life cycle of anadromous charr is spent in the river, followed by an intermediate period of a year in the salt wedge area and then by a 2- or 3-month period in salt water before returning to the river. Bigger charr started upstream migration earlier in the season than smaller charr. Migration peaks in 1979 were synchronized with the new moon. Fish movements in the estuary were greater during spring tides than neap tides. Diel activity was highest in the day in the estuary whereas the inverse situation occurred in the river. From tags returns, it was concluded that anadromous brook charr had a strong homing tendency.