Incursions of Sea Lamprey, Petromyzon marinus , and Striped Bass, Morone saxatilis , in Labrador waters: Episodic events or evidence of a northward range expansion?

2021 ◽  
Author(s):  
Travis E. Van Leeuwen ◽  
David Cote ◽  
Christina Pretty ◽  
Joseph Townley ◽  
Rebecca Poole ◽  
...  
2020 ◽  
Vol 142 ◽  
pp. 47-53
Author(s):  
K Béland ◽  
G Séguin ◽  
S Lair

An unusually high mortality rate due to verminous (Philometra rubra) coelomitis was documented in wild-hatched striped bass Morone saxatilis raised in a fish hatchery as part of a stock restoration program. To decrease the parasitic burden and therefore potentially minimize mortality, the effectiveness of 2 different anthelmintics was evaluated. Two trials were conducted on wild-collected fingerlings naturally infected by P. rubra. In 2006, 144 yearling fish were randomly assigned to 4 experimental groups: (1) levamisole (Levasol®) at 2 mg l-1 via immersion for 8 h once weekly for 3 wk; (2) levamisole at a dose of 2.5 mg kg-1 biomass via feed once daily for 7 d; (3) emamectin benzoate (Slice®) at a dose of 0.05 mg kg-1 biomass via feed once daily for 7 d; and (4) control. Emamectin successfully eliminated live nematodes in 84.9% of the fish, whereas the administration of levamisole, either via immersion or feed, was not successful in significantly reducing the number of live P. rubra. In 2007, the administration of the same dosage of emamectin to approximately 1000 naturally infected yearling striped bass was associated with a 100% mortality rate of P. rubra in the 30 fish randomly examined 5 wk after the beginning of the treatment. Results of these trials indicate that, at the dosage used, the administration of emamectin at the end of the summer is safe for striped bass yearlings and considerably reduces the prevalence and intensity of the infection by this parasite.


2019 ◽  
Vol 41 (4) ◽  
pp. 507-520 ◽  
Author(s):  
L Vanalderweireldt ◽  
P Sirois ◽  
M Mingelbier ◽  
G Winkler

Abstract After being extirpated from the St. Lawrence River in the 1960s, striped bass (Morone saxatilis) were reintroduced to the estuary in 2002 and by 2008, they were naturally reproducing. To document the habitat use and feeding ecology of this reintroduced population, we examined the gut contents of 333 larvae and juveniles. Samples were collected in four estuarine habitats in 2014: the upstream freshwater section (UP), the oligohaline (O-ETM) and the mesohaline (M-ETM) estuarine turbidity maximum zones, and the downstream polyhaline section (DOWN). In June, pelagic larvae developed in the UP and the O-ETM, feeding mainly on copepods such as Eurytemora affinis. The O-ETM exhibited better suitable feeding conditions compared to the UP, likely due to the presence of Bosmina sp. as a primary prey. After July, striped bass shifted to larger prey items, consuming mainly dipteran pupa in upstream littoral habitats and gammarids and mysids in downstream habitats. In the early summer, the UP provided a high-quality nursery habitat and as the season progressed, the smallest juveniles dispersed downstream and improved their feeding success by exploiting a new feeding niche. This observation suggests that being distributed throughout the estuary may increase the potential survival of striped bass early life stages.


1980 ◽  
Vol 37 (11) ◽  
pp. 1989-2006 ◽  
Author(s):  
Everett Louis King Jr.

Criteria for the classification of marks inflicted by sea lamprey (Petromyzon marinus) into nine categories were developed from laboratory studies in an attempt to refine the classification system used in field assessment work. These criteria were based on characteristics of the attachment site that could be identified under field conditions by unaided visual means and by touching the attachment site. Healing of these marks was somewhat variable and was influenced by the size of lamprey, duration of attachment, severity of the wound at lamprey detachment, season and water temperature, and by other less obvious factors. Even under laboratory conditions staging of some wounds was difficult, especially at low water temperatures. If these criteria are to be used effectively and with precision in the field, close examination of individual fish may be required. If the feeding and density of specific year-classes of sea lampreys are to be accurately assessed on an annual basis, close attention to the wound size (as it reflects the size of the lamprey's oral disc) and character of wounds on fish will be required as well as consideration of the season of the year in which they are observed.Key words: sea lamprey, attack marks, lake trout, Great Lakes


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