scholarly journals A decade of monitoring Atlantic cod Gadus morhua spawning aggregations in Massachusetts Bay using passive acoustics

2020 ◽  
Vol 635 ◽  
pp. 89-103 ◽  
Author(s):  
PE Caiger ◽  
MJ Dean ◽  
AI DeAngelis ◽  
LT Hatch ◽  
AN Rice ◽  
...  

Atlantic cod Gadus morhua populations in the northeast USA have failed to recover since major declines in the 1970s and 1990s. To rebuild these stocks, managers need reliable information on spawning dynamics in order to design and implement control measures; discovering cost-effective and non-invasive monitoring techniques is also favorable. Atlantic cod form dense, site-fidelic spawning aggregations during which they vocalize, permitting acoustic detection of their presence at such times. The objective of this study was to detect spawning activity of Atlantic cod using multiple fixed-station passive acoustic recorders to sample across Massachusetts Bay during the winter spawning period. A generalized linear modeling approach was used to investigate spatio-temporal trends of cod vocalizing over 10 consecutive winter spawning seasons (2007-2016), the longest such timeline of any passive acoustic monitoring of a fish species. The vocal activity of Atlantic cod was associated with diel, lunar, and seasonal cycles, with a higher probability of occurrence at night, during the full moon, and near the end of November. Following 2009 and 2010, there was a general decline in acoustic activity. Furthermore, the northwest corner of Stellwagen Bank was identified as an important spawning location. This project demonstrated the utility of passive acoustic monitoring in determining the presence of an acoustically active fish species, and provides valuable data for informing the management of this commercially, culturally, and ecologically important species.

2013 ◽  
Vol 70 (3) ◽  
pp. 628-635 ◽  
Author(s):  
Keith M. Hernandez ◽  
Denise Risch ◽  
Danielle M. Cholewiak ◽  
Micah J. Dean ◽  
Leila T. Hatch ◽  
...  

Abstract Hernandez, K. M., Risch, D., Cholewiak, D. M., Dean, M. J., Hatch, L. T., Hoffman, W. S., Rice, A. N., Zemeckis, D., and Van Parijs, S. M. 2013. Acoustic monitoring of Atlantic cod (Gadus morhua) in Massachusetts Bay: implications for management and conservation. – ICES Journal of Marine Science, 70: 628–635. Atlantic cod (Gadus morhua) stocks in northeastern US waters are depleted and stock recovery has been slow; research into the spawning behaviour of this species can help inform conservation and management measures. Male cod produce low-frequency grunts during courtship and spawning. Passive acoustic monitoring (PAM) offers a different perspective from which to investigate the occurrence, spatial extent and duration of spawning cod aggregations. A marine autonomous recording unit was deployed in the “Spring Cod Conservation Zone” (SCCZ) located in Massachusetts Bay, western Atlantic, to record cod grunts from April–June 2011. Cod grunts were present on 98.67% of the recording days (n = 75 days). They occurred across all 24 h, although significantly more grunts were found during the day than night-time (p = 0.0065). Grunt durations ranged from 57–360 ms, and the fundamental frequency and second harmonic had mean peak frequencies of 49.7 ± 5.6 and 102.9 Hz ± 10.9 sd, respectively. Cod grunt rates were low compared with those reported for other spawning fish, and may be indicative of diel movement patterns. Next steps will focus on expanding PAM coverage within the SCCZ, alongside prospecting for unknown spawning grounds within existing archival data.


2013 ◽  
Vol 94 (6) ◽  
pp. 1117-1125 ◽  
Author(s):  
Anita Murray ◽  
Aaron N. Rice ◽  
Christopher W. Clark

Humpback whales (Megaptera novaeangliae) are known to utilize Massachusetts Bay as a feeding ground in the spring and summer, during the annual migration of the Gulf of Maine sub-population. However, there is a limited understanding of the pattern of humpback whale occurrence in this region outside of the feeding period. Passive acoustic monitoring of Massachusetts Bay over a two-year period, revealed an extended presence of acoustically active humpback whales throughout a majority of the study period (87%; 633 days of presence out of 725 days of acoustic monitoring). Humpback whale presence oscillated between lengthy periods of consistent presence (April to December) and relatively shorter periods of variable presence (December to March). Seasonal variation in presence was evident during three distinct phases: (1) maximum-presence from spring to early winter; (2) variable-presence in early winter and early spring; and (3) minimum-presence mid-winter. The variation in seasonal presence was concurrent with coarse migratory patterns of humpback whales, and yearly variations in presence presumably reflect a shift in the influx and efflux of whales between years. The extended presence of humpbacks in this area suggests that Massachusetts Bay is an important, year-round habitat for the Gulf of Maine sub-population, and may warrant revision of management and regulatory practices to reflect this presence.


2021 ◽  
pp. e01710
Author(s):  
Dana S. Reid ◽  
Connor M. Wood ◽  
Sheila A. Whitmore ◽  
William J. Berigan ◽  
John J. Keane ◽  
...  

1999 ◽  
Vol 56 (1) ◽  
pp. 97-104 ◽  
Author(s):  
Jeffrey A Hutchings ◽  
Todd D Bishop ◽  
Carolyn R McGregor-Shaw

We quantified individual differences in Atlantic cod, Gadus morhua, reproductive behaviour at a field-reported spawning density under experimental conditions. Marked individuals (nine females, seven males) were observed twice daily and videotaped continuously for 9 weeks at ambient photoperiod and temperature in a large tank (60 m3). Agonistic interactions appeared to maintain a size-based dominance hierarchy among males. Multiple paternity per spawning bout, revealed by microsatellite DNA analysis, suggested a link between dominance and fertilization success. Interactions between sexes were dominated by the circling of females by males. Predicated by vertical separation from males, and after descending to the bottom, a motionless female would be circled up to 17 times, often by one male per circling bout but by several males throughout the spawning period. Although circling frequency increased with male dominance and male body size, initiation and termination of this behaviour appeared to be under female control. Circling provides opportunities for males to gain individual access to reproductive females and for females to assess the quality of potential mates. Our evidence for nonrandom mate choice and for male-male competition and display has implications for Atlantic cod mating systems and effects of fishing on their reproductive success.


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