Early Life History Predator-Prey Interactions and Habitat Use of the American Eel and American Conger

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By Alison Enchelmaier, RJD Graduate Student Declines in the American eel, Anguilla rostrata, have raised interest in studying the species’ early life history. Potential causes could include overfishing, increased predation, and habitat loss; but determining the cause is difficult due to the American eel’s complex life history. One potential factor, predation, is important to consider as the refuge value of estuarine nursery habitats are being reevaluated (Musumeci et al., 2014).Another factor is habitat competition. American eels arrive in North Atlantic estuaries in their early juvenile stage called glass eels, from the winter to spring. This overlaps with another species called … Continue reading

Evidence for collective navigation in salmon for homeward migration

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By Hanover Matz, RJD Intern The long migrations undertaken by Atlantic and Pacific salmon to reach their spawning grounds are known by many. Salmon are anadromous; they spend their adult lives foraging at sea, and then return to the freshwater rivers of their births to spawn and reproduce. How this remarkable feat is accomplished by the salmon with such accuracy is believed to be a combination of geomagnetic and olfactory cues. However, Berdahl et al. examined evidence that salmon may also be relying on social interactions and collective behavior in order to navigate to their natal homes. The authors hypothesized … Continue reading

Maltreatment as hatchlings predisposes Nazca boobies to more frequent violent episodes as adults

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By Daniela Escontrela, RJD Intern The Galapagos Islands are home to four species of native and endemic boobies: the blue footed boobies, the masked boobies, the Nazca boobies and the red footed boobies. The name for the boobies comes from the name “bobo” which is a Spanish term for fool or clown. They are all part of the Gannet family which is also found in North America. These birds have dagger like beaks and are accustomed to diving into the ocean for their food. Although the three species of boobies nest and breed in approximately the same territories they don’t … Continue reading

Economic vs. Conservation: Trade-offs between Catch, Bycatch, and Landed Value in the American Samoa Longline Fishery

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By Laurel Zaima, RJD Undergraduate Intern Commercial fisheries have prioritized maximum economic profit over the ecological distresses caused by their fishing practices. Consequently, unsustainable fishing practices hook high amounts of bycatch in relation to the amount of the target species. Bycatch are the animals that are accidentally caught and discarded due to lack of value, insufficient size, damaged, or regulatory reasons. Bycatch has detrimental effects on the populations of a diversity of marine species; therefore, has altered ecological relationships and the economics of commercial fisheries. A seemingly obvious solution to this threat would be the implementation of commercial fishing gear … Continue reading

Real-Time Spatial Management as a Bycatch Mitigation Measure

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By Hannah Calich, RJD Graduate Student Bycatch, or the unintentional capture of non-target species, has negative biological, economical and social consequences (figure 1). Reducing bycatch has been a fisheries management priority in the US for many years and is increasingly becoming a priority in European fisheries as well. While technical, regulatory and social approaches have all been recognized as ways to reduce bycatch, they are not always effective (Little et al., 2014).     Currently, the primary methods of reducing bycatch involve either creating fishing closures or improving the selectivity of fishing gear. The primary problems with fishing closures are … Continue reading

Whale Conservation in the Mediterranean

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By Jessica Wingar, RJD Intern Conservation of threatened species is very critical in order to maintain the state of our oceans. There is a wide range of reasons for why the species needs to be conserved from threat of boat strikes to disease outbreak. However, humans cause many of these threats. In an effort to protect these threatened species from humans, marine protected areas, or MPAs, can be established. In this study, researchers were looking at whether it would be more effective to establish a series of MPAs or to restrict shipping through the International Maritime Organization, IMO, in order … Continue reading