Department of Fisheries Oceanography Masters Thesis Defense
When: Monday,
May 9, 2016
1:00 PM
-
2:00 PM
Where: > See description for location
Description: The School for Marine Science and Technology
Department of Fisheries Oceanography
Masters Thesis Defense Announcement
Validation of Age Determination Methods for Monkfish
(Lophius americanus)
By
Cristiana Bank
Advisor
Steve Cadrin
Monday, May 9, 2016
1:00 pm
SMAST II, Room 157
200 Mill Rd, Fairhaven, MA
Abstract:
Monkfish, Lophius americanus, support an important commercial fishery in the Northeastern United States. Despite healthy stock status, annual catch limits are relatively low, largely because of scientific uncertainty in the stock assessment. The age determination method for monkfish has not been validated, contributing uncertainty in the assessment. Annual growth rings are currently counted on the vertebrae and are assumed to follow a seasonal pattern. To validate the vertebral ageing protocol and to explore alternative ageing methods, we injected oxytetracycline or fluorexon into individual monkfish, kept them alive in the laboratory, and subjected them to a seasonal cycle of temperature, light, and feeding. Monkfish were also injected in the field with the same chemical markers as part of an on-going tagging study. The chemical left a visible mark on the growth ring that was forming at the time of injection. Vertebrae, otoliths, and illicia were analyzed from fish that lived six months or more after marking, from both the laboratory study and the field recaptures. Digital images were taken with an ultraviolet light to illuminate the mark and reflected light to show the growth rings. An experienced monkfish age reader determined age from vertebrae and each annulus after the chemical mark was identified. Results indicate that annuli counts on vertebrae cannot be used to accurately determine the age of monkfish, irregular growth of the otolith prohibits its use as a reliable age structure, and age determination using illicia is the most promising.
For additional information, please contact Sue Silva at s1silva@umassd.edu.
Department of Fisheries Oceanography
Masters Thesis Defense Announcement
Validation of Age Determination Methods for Monkfish
(Lophius americanus)
By
Cristiana Bank
Advisor
Steve Cadrin
Monday, May 9, 2016
1:00 pm
SMAST II, Room 157
200 Mill Rd, Fairhaven, MA
Abstract:
Monkfish, Lophius americanus, support an important commercial fishery in the Northeastern United States. Despite healthy stock status, annual catch limits are relatively low, largely because of scientific uncertainty in the stock assessment. The age determination method for monkfish has not been validated, contributing uncertainty in the assessment. Annual growth rings are currently counted on the vertebrae and are assumed to follow a seasonal pattern. To validate the vertebral ageing protocol and to explore alternative ageing methods, we injected oxytetracycline or fluorexon into individual monkfish, kept them alive in the laboratory, and subjected them to a seasonal cycle of temperature, light, and feeding. Monkfish were also injected in the field with the same chemical markers as part of an on-going tagging study. The chemical left a visible mark on the growth ring that was forming at the time of injection. Vertebrae, otoliths, and illicia were analyzed from fish that lived six months or more after marking, from both the laboratory study and the field recaptures. Digital images were taken with an ultraviolet light to illuminate the mark and reflected light to show the growth rings. An experienced monkfish age reader determined age from vertebrae and each annulus after the chemical mark was identified. Results indicate that annuli counts on vertebrae cannot be used to accurately determine the age of monkfish, irregular growth of the otolith prohibits its use as a reliable age structure, and age determination using illicia is the most promising.
For additional information, please contact Sue Silva at s1silva@umassd.edu.
Contact: > See Description for contact information
Topical Areas: School for Marine Sciences and Technology, SMAST Seminar Series