Abstract Long-term monitoring of the wild salmon (Salmo salar L.) stock of the Simojoki river and the stocked hatchery-reared salmon parr and smolts has provided a considerable amount of information on the development of the stock and factors affecting it. Data on the relationships between wild and reared salmon were collected by tagging and trapping both smolts and adult salmon having either a wild or reared background. The tag recapture rate of wild smolts was about twice as high as that of smolts stocked as two-year-olds and slightly greater than for smolts stocked as parr. When survival was measured in relation to the smolt size, the difference between the wild and reared smolts was even greater, and it seemed to be emphasized in years with a low survival rate. The difference observed between the wild and reared salmon in the smolt phase generally disappeared in the adult phase. When adult salmon returned to the river to spawn the difference in the timing of the ascent depended more on the age or sex of the salmon, and less on their origin. Similarly, the survival of adult salmon in the river before or after spawning and later after returning to the sea depended on the sex and age of the fish. The origin of fish affected their behaviour, the reared salmon wandering more than wild adults before settling down into spawning areas. When the yield of wild and reared smolts as returning adults was compared, the wild smolts gave the best results, although the survival from smolt to adult was low in all smolt groups, probably due to the high fishing pressure in the sea. The smolts stocked as parr and those stocked as two-year-old fish were similar in this respect. The former group gave better results if the yield was measured as the number of returning multi-sea-winter adults, while the latter group gave better results if one-sea-winter grilse were also included in the yield. The low yield of adult salmon from stocking and the generally low survival of smolt groups irrespective of their origin emphasises the importance of fishing regulations as a tool in the maintenance or enhancement of naturally reproducing salmon stocks. However, despite the low profitability of stocking, it probably safeguarded the existence of the wild Simojoki salmon stock during its critical phase in the early 1990s. At that time the fishing regulations were not strict enough to prevent the alarming decrease in the salmon stock, and the adult spawners produced by stocking of young salmon may have had a relatively higher value than their number suggests.

>Magister Scientiae - MSc / Hydromedusae are mostly carnivorous planktivores that under ideal conditions can reproduce and accumulate to form dense masses of jellyfish, known as blooms. These jellyfish blooms may have various impacts on their surrounding biota and in severe cases have the potential to result in ecosystem-wide changes. This study investigated assemblages of hydromedusae within the southern Benguela ecosystem, between the years 2000 and 2006. The samples analyzed were collected as part of routine Spawner Biomass Surveys conducted by the Department of Environmental Affairs: Ocean and Coasts (previously Marine and Coastal Management) using Bongo nets. Two hundred and forty two of the samples collected during the spring months, October and November, were analyzed. Environmental variables including (amongst others) sea surface temperature (SST), sea surface salinity (SSS), sea surface oxygen (SSO) and fluorescence (as a proxy for Chlorophyll a concentration) were measured to observe their influence on medusoid assemblages, distribution, abundance and diversity. Assemblages of hydromedusae were represented by 69 species and were dominated by Siphonophora and Leptomedusae. Mean abundance of hydromedusae were highest in 2005 (3.15 ind.m-³, SD 3.21) and lowest in 2002 (0.50 ind.m-³, SD 0.70). Trends in abundance displayed a general bell-shaped curve relationship with SST. The random-effects meta-analysis model revealed, across all years and all medusaoid classes that SSS (R=0.469), latitude (R=0.223), bottom fluorescence (R=0.533), mean fluorescence (R=0.338) and volume filtered (R=-0.408) were all significant factors in driving medusoid abundance at p<0.05. Medusoid diversity displayed a positive correlation to both temperature and salinity. A BIOENV analysis was used to explore the environmental factors that best described the variation observed in the biological assemblages. The results from this analysis suggest that SSS and bottom oxygen (BO) are the environmental factors that most influence the composition of medusoid assemblages.

Life history of Phoxinus tennesseensis (Tennessee dace), a species deemed "in need of management" in Tennessee and endangered in Virginia, was investigated from August 1999 to May 2001 on 2 populations in Trinkle Creek and Timbertree Branch, Sullivan County, Tennessee. Samples were taken monthly to provide information on growth, reproductive biology, preferred habitat, and demography. Observations were made during the breeding season to determine spawning strategy. Breeding season lasted from April to June. Spawning occurred over the nest of Semotilus atromaculatus (creek chub) and Campostoma anomalum (central stoneroller). With 1 to 10 females, 20 to 45 male dace gathered over the nest. Phoxinus tennesseensis populations have 4 age classes. The normal life span of the dace was about 2 years with 1st year fish constituting a majority of the total population. Historic populations and potentially new populations were sampled to determine the current distribution in Northeast Tennessee.

Most corals worldwide are broadcast spawners that rely on synchronous gamete release for successful fertilization. Spawning synchrony may also decrease the probability of heterospecific fertilization that may produce maladaptive hybrids. Despite the importance of reproductive timing, researchers have only recently begun to collect spawning data across coral species in the Caribbean, but these data remain to be analyzed. This study investigates interannual, seasonal, and environmental patterns that may influence Caribbean scleractinian spawning times. The number of spawning observations varies widely among location and species. Most spawning observations were collected in Florida, Curaçao, and Flower Garden Banks National Marine Sanctuary. Acropora palmata, A. cervicornis, and Orbicella species were the most documented. The Orbicella spp. were very consistent for spawning day annually, while the acroporids were less reliable. However, the acroporids were more consistent for spawning time in minutes after sunset between years. Season and moon cycles were obvious proximate cues for spawning, but a strong influence from wind and tides was absent. Acropora cervicornis was the only species in this study which spawning was significantly affected by water temperature. For some scleractinians, the day of spawning was significantly affected by mass bleaching events; spawning could occur on earlier days than in previous years for up to two years after the event. This study highlights existing data gaps for Pseudodiploria clivosa, A. prolifera and Siderastrea siderea. Documenting spawning patterns is crucial to better understand the potential impacts of future threats on the already imperiled Caribbean corals at risk from reproductive failure.