A review on broodstock nutrition of marine pelagic spawners: the curious case of the freshwater eels (Anguilla spp.)

To sustain eel aquaculture, development of reproduction in captivity is vital. The aim of this review is to assess our current knowledge on the nutrition of broodstock eels in order to improve the quality of broodstock under farming conditions, drawing information from wild adult eels and other marine pelagic spawners. Freshwater eels spawn marine pelagic eggs with an oil droplet (type II), and with a large perivitelline space. Compared with other marine fish eggs, eel eggs are at the extreme end of the spectrum in terms of egg composition, even within this type II group. Eel eggs contain a large amount of total lipids, and a shortage of neutral lipids has been implied a cause for reduced survival of larvae. Eel eggs have higher ARA but lower EPA and DHA levels than in other fish. Too high levels of ARA negatively affected reproduction in the Japanese eel, although high levels of 18:2n-6 in the eggs of farmed eels were not detrimental. The total free amino acid amount and profile of eel eggs appears much different from other marine pelagic spawners. Nutritional intervention to influence egg composition seems feasible, but responsiveness of farmed eels to induced maturation might also require environmental manipulation. The challenge remains to succeed in raising European eel broodstock with formulated feeds and to enable the procurement of viable eggs and larvae, once adequate protocols for induced maturation have been developed

Mödrars sociala status på den svenska arbetsmarknaden : Rekryterares syn på och attityder till moderskapetinom den privata sektorn

Syftet med denna uppsats är att belysa hur rekryterare inom den privata sektorn ser på moderskapet inför en rekrytering. Frågeställningarna i studien handlar om hur rekryterarna uppfattar moderskapet när de skall anställa, vilken påverkan moderskapet har i rekryteringssammanhang samt rekryterarnas bild av hur idealarbetaren ser ut. Det empiriska materialet består av intervjuer med fem rekryterare som är yrkesverksamma inom den privata sektorn. I studien framkom det att mödrar ses som den primära vårdtagaren av barn. Där de bidragande orsakerna till detta dels var en ekonomisk faktor där män anses tjäna bättre än kvinnor, men där även de traditionella könsrollerna ansågs som en bidragande faktor.The purpose of this essay is to illuminate how recruiters within the private sector look at motherhood before recruiting. The questions at issue in this study deal with how recruiters look at motherhood when they are about to recruit, what effect motherhood has when it comes to hiring and the recruiters image of the ideal worker. The empirical material contains five interviews with recruiters that work with recruiting within the private sector. The study showed that mothers are viewed as the primary caretaker of children. Because of economical factors such as men considers to have a higher salary compare women, and also traditional gender roles in the Swedish society considers to being a contributing factor

The spreading of Anguillicola crassus in freshwater lakes in Sweden

The first record of Anguillicola crassus in Sweden was made in 1987. Nine years later, the swimbladder parasite was well established not only in thermal discharge areas but in other brackish waters along the coasts as well as in some freshwater lakes. In comparison with certain localities affected by thermal discharges, the infection rate has been much slower in two inland eel stocks and in one coastal stock monitored in this study. There are strong indications that the parasite was introduced into several freshwater lakes as a consequence of active stocking measures using yellow eels caught at the Swedish west coast

The spreading of Anguillicola crassus in freshwater lakes in Sweden

The first record of Anguillicola crassus in Sweden was made in 1987. Nine years later, the swimbladder parasite was well established not only in thermal discharge areas but in other brackish waters along the coasts as well as in some freshwater lakes. In comparison with certain localities affected by thermal discharges, the infection rate has been much slower in two inland eel stocks and in one coastal stock monitored in this study. There are strong indications that the parasite was introduced into several freshwater lakes as a consequence of active stocking measures using yellow eels caught at the Swedish west coast

Fecundity of silver-phase eels (anguilla anguilla) from different habitat types and geographic locations

The reproductive ecology of European eel (Anguilla anguilla) is poorly understood, though information on life-history traits such as fecundity is necessary for appropriate management of this critically endangered species. During the growth period of the life cycle, yellow-phase eels can be resident in different habitat types (e.g. salinity ranging from freshwater to marine) over a wide geographic distribution. Consequently, maturing silver-phase eels migrating back to the oceanic spawning grounds can display considerable variation in certain life-history traits depending on their habitat and/or geographic origin. Few fecundity estimates are available from wild A. anguilla, and no investigation of the effects of habitat type (i.e. salinity) or geographic location on variation in fecundity has been undertaken. To assess the former, we examined silver-phase eels which had predominantly been resident in freshwater (Lake Malaren, Sweden) or brackish (Baltic Sea) habitats. Despite Lake Malaren eels generally being larger, there was no difference in the fecundity-body size relationship between these salinity zones. Second, we determined if fecundity differed between silver-phase eels sampled from different geographic locations: Lake Malaren and the Baltic Sea outlet in Sweden, the River Shannon in Ireland (northwest Europe) and Vistonis Lake in Greece (eastern Mediterranean). Our results showed that silver-phase eels from Sweden (Lake Malaren and Baltic Sea outlet) and Greece were significantly more fecund at a given body size than those from Ireland. Spawner models and conservation policies should therefore take account of eel geographic origin in particular when incorporating this life-history parameter

Fecundity of silver-phase eels (anguilla anguilla) from different habitat types and geographic locations

The reproductive ecology of European eel (Anguilla anguilla) is poorly understood, though information on life-history traits such as fecundity is necessary for appropriate management of this critically endangered species. During the growth period of the life cycle, yellow-phase eels can be resident in different habitat types (e.g. salinity ranging from freshwater to marine) over a wide geographic distribution. Consequently, maturing silver-phase eels migrating back to the oceanic spawning grounds can display considerable variation in certain life-history traits depending on their habitat and/or geographic origin. Few fecundity estimates are available from wild A. anguilla, and no investigation of the effects of habitat type (i.e. salinity) or geographic location on variation in fecundity has been undertaken. To assess the former, we examined silver-phase eels which had predominantly been resident in freshwater (Lake Malaren, Sweden) or brackish (Baltic Sea) habitats. Despite Lake Malaren eels generally being larger, there was no difference in the fecundity-body size relationship between these salinity zones. Second, we determined if fecundity differed between silver-phase eels sampled from different geographic locations: Lake Malaren and the Baltic Sea outlet in Sweden, the River Shannon in Ireland (northwest Europe) and Vistonis Lake in Greece (eastern Mediterranean). Our results showed that silver-phase eels from Sweden (Lake Malaren and Baltic Sea outlet) and Greece were significantly more fecund at a given body size than those from Ireland. Spawner models and conservation policies should therefore take account of eel geographic origin in particular when incorporating this life-history parameter