scholarly journals Potential growth of pelagic juvenile cod in relation to the 1978–2006 winter–spring zooplankton on the Northeast US continental shelf

2015 ◽  
Vol 72 (9) ◽  
pp. 2549-2568 ◽  
Author(s):  
R. G. Lough ◽  
T. Kristiansen
Keyword(s):  
Time Series ◽  
New England ◽  
Gulf Of Maine ◽  
Climatic Conditions ◽  
Calanus Finmarchicus ◽  
Georges Bank ◽  
Potential Growth ◽  
Lower Growth ◽  
Centropages Typicus ◽  
Pelagic Juvenile

Abstract Environmental conditions during the pelagic juvenile cod period determine their fitness to survive settlement as demersal juveniles (0-group) and recruitment. This study examines the potential growth of pelagic juvenile cod in five areas of the New England Shelf based on time series of zooplankton and ocean temperature from surveys. An individual-based model was used to estimate the temporal variation in growth of juvenile cod at each survey station based on available prey of appropriate sized copepods of Calanus finmarchicus, Pseudocalanus spp., Centropages typicus, and Centropages hamatus. Mean juvenile cod growth was low (1–7% d−1) during January–February and March–April time series across all areas, Gulf of Maine (GOM), Eastern Georges Bank, Western Georges Bank, southern New England to Middle Atlantic Bight (MAB). Growth increased significantly in May–June with the seasonal increase in copepod density and temperature generally from South to North. The 1990–1999 warm years had the highest growth of 12–14% d−1 compared with the cooler 2000–2006 years and colder 1978–1989 years of similarly lower growth of 8–11% d−1. Growth in the MAB stayed the same 13% d−1 as in 1990–1999, whereas GOM growth decreased significantly to ∼6% d−1. High prey densities during May–June 1990–1999 for Georges Bank and GOM, followed by a strong decrease in 2000–2006 may explain the decrease in growth during the same periods. While all four copepod species contributed to potential growth, C. typicus, a more southern species, could be the more important prey for juveniles in the coastal areas during all months in contrast to Pseudocalanus spp. for the larvae. Centropages typicus also is the most adaptable and likely species able to expand and thrive under warmer climatic conditions, which could be of significance to future recruitment. Age-1 recruitment for Georges Bank cod was found to be related to juvenile growth.

scholarly journals Zooplankton abundance trends on Georges Bank, 1977–2004

2007 ◽  
Vol 64 (5) ◽  
pp. 909-919 ◽  
Author(s):  
Joseph Kane
Keyword(s):  
Calanus Finmarchicus ◽  
Zooplankton Abundance ◽  
Georges Bank ◽  
Total Zooplankton ◽  
Key Factors ◽  
The Past ◽  
Abundance Trends ◽  
Temora Longicornis ◽  
Northeast Us ◽  
Centropages Typicus

Abstract Kane, J. 2007. Zooplankton abundance trends on Georges Bank, 1977–2004. – ICES Journal of Marine Science, 64: 909–919. Interannual trends in Georges Bank zooplankton abundance are described and related to variations in environmental variables for the period 1977–2004. Total zooplankton counts increased to above average levels in 1989 and stayed over or close to average through 2004. This analysis identified a group of taxa including Centropages typicus, Metridia lucens, and Temora longicornis that had similar interannual patterns of abundance. All these taxa increased sharply in the early 1990s and remained high through 2001. Some taxa declined sharply in 2002, others have continued elevated through 2004. Total zooplankton counts in the past two years were also boosted by a substantial increase in the abundance of the copepod Calanus finmarchicus. Evidence is presented that these changes may be related to variations in Scotian Shelf inflow, which freshened water on the Northeast US continental shelf, perhaps increasing both primary production and the influx of zooplankton into the region. There was a positive correlation between the biomass of pelagic predators and the abundance of several zooplankton taxa, suggesting that bottom-up processes and advective supply are the key factors that regulate the Georges Bank foodweb.

Advancing an Ecosystem Approach in the Gulf of Maine

2012 ◽  
Keyword(s):  
New England ◽  
Gulf Of Maine ◽  
Ecosystem Approach ◽  
Calanus Finmarchicus ◽  
Massachusetts Bay ◽  
Species Dominance ◽  
Dramatic Decline ◽  
Salinity Water ◽  
Peak Abundance ◽  
Ocean Observing

<i>Abstract</i> .—In a collaborative project with a number of New England commercial fishermen, zooplankton was sampled two to three times a month between 2003 and 2005 at the GoMOOS (Gulf of Maine Ocean Observing System) Buoy “B” and between 2003 and 2008 at a station on Jeffreys Ledge in the western Gulf of Maine. Additionally, during 2007 and 2008 zooplankton and ichthyoplankton were sampled semimonthly at stations located in Massachusetts Bay and Ipswich Bay, New Hampshire. The authors report here on seasonal and interannual patterns in biomass, diversity, and abundance in the zooplankton at the Jeffreys Ledge station and in the ichthyoplankton at the Massachusetts and Ipswich Bay stations. Notable is the dominance of <i>Calanus finmarchicus </i> on Jeffreys Ledge and the dramatic decline in summer abundance of this species between 2003 and 2005, perhaps related to a shift to lower salinity water during this same period. Interannual differences in timing of peak abundance, and in species dominance of ichthyoplankton, were observed between 2007 and 2008. While these time series provide information and insight about change in the coastal planktonic communities in the western Gulf of Maine, currently there are no observing programs that sample coastal communities at frequency sufficient to show seasonal and interannual change in this region.

scholarly journals Do environmental factors affect recruits per spawner anomalies of New England groundfish?

2005 ◽  
Vol 62 (7) ◽  
pp. 1394-1407 ◽  
Author(s):  
Jon Brodziak ◽  
Loretta O'Brien
Keyword(s):  
Environmental Factors ◽  
New England ◽  
Gulf Of Maine ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Winter Flounder ◽  
Water Volume ◽  
Melanogrammus Aeglefinus ◽  
Georges Bank ◽  
Yellowtail Flounder

Abstract We evaluated the influence of environmental factors on recruits per spawner (RS) anomalies of 12 New England groundfish stocks. Nonparametric methods were used to analyse time-series of RS anomalies derived from stock-recruitment data in recent assessments. The 12 stocks occur in three geographic regions: the Gulf of Maine (cod Gadus morhua, redfish Sebastes fasciatus, winter flounder Pseudopleuronectes americanus, American plaice Hippoglossoides platessoides, witch flounder Glyptocephalus cynoglossus, and yellowtail flounder Limanda ferruginea), Georges Bank (cod, haddock Melanogrammus aeglefinus, and yellowtail flounder), and Southern New England (summer flounder Paralichthys dentatus, yellowtail flounder, and winter flounder). Randomization tests were applied to detect years when RS anomalies were unusually high or low for comparison with oceanographic conditions such as the 1998 intrusion of Labrador Subarctic Slope water into the Gulf of Maine region. Randomization methods were also used to evaluate the central tendency and dispersion of all RS anomalies across stocks. Average RS anomalies were significantly positive in 1987 across stocks and regions, indicating that environmental forcing was coherent and exceptional in that year. Responses of RS values of individual stocks to lagged and contemporaneous environmental variables such as the North Atlantic Oscillation (NAO) index, water temperature, windstress, and shelf water volume anomalies were evaluated using generalized additive models. Overall, the NAO forward-lagged by 2 years had the largest impact on RS anomalies. This apparent effect is notable because it could provide a leading indicator of RS anomalies for some commercially exploited stocks. In particular, the three primary groundfish stocks on Georges Bank (cod, haddock, and yellowtail flounder) all exhibited positive RS anomalies when the NAO2 variable was positive.

scholarly journals Multiyear variability of phytoplankton abundance in the Gulf of Maine

2011 ◽  
Vol 68 (9) ◽  
pp. 1833-1841 ◽  
Author(s):  
Joseph Kane
Keyword(s):  
Time Series ◽  
Gulf Of Maine ◽  
Late Summer ◽  
Environmental Variable ◽  
Calanus Finmarchicus ◽  
Phytoplankton Abundance ◽  
Low Salinity ◽  
The North ◽  
The Common ◽  
The North Atlantic Oscillation

Abstract Kane, J. 2011. Multiyear variability of phytoplankton abundance in the Gulf of Maine. – ICES Journal of Marine Science, 68: 1833–1841. Significant interannual changes in phytoplankton abundance were identified in the Continuous Plankton Recorder time-series collected in the Gulf of Maine from 1961 to 2008. Abundance levels of nearly all the common taxa began to increase in 1990 and remained elevated through 2001. During that period, total numbers were above average throughout the year, with an unusual bloom in late summer. Multivariate analysis of abundance identified three consecutive multiyear periods of varying abundance levels: low to average from 1961 to 1989, above average or very high from 1990 to 2001, and below average thereafter, through 2008. Phytoplankton abundance patterns were closely aligned to the rising trends displayed by several of the common zooplankton taxa. The North Atlantic Oscillation was the only environmental variable examined that showed some association with time-series abundance trends of plankton. The index was primarily positive in the 1990s, which would favour the propagation of warm, nutrient-rich slope water into the region. Perhaps the increased influx of this water, along with feedback enrichment from abundant zooplankton stocks and reduced top-down control by the relative scarcity of the dominant copepod Calanus finmarchicus, combined with a low salinity to make the 1990s a unique decade for plankton change in the Gulf of Maine.

A bioeconomic model of marine sanctuaries on Georges Bank

2000 ◽  
Vol 57 (6) ◽  
pp. 1307-1319 ◽  
Author(s):  
Daniel S Holland
Keyword(s):  
New England ◽  
Gulf Of Maine ◽  
Georges Bank ◽  
Bioeconomic Model ◽  
Seasonal Movement ◽  
Southern New England ◽  
Modeling Methodology ◽  
Spawning Stock ◽  
Age Structured ◽  
Groundfish Fishery

An empirically estimated fleet dynamics model for New England trawlers is integrated with spatial, age-structured models of primary groundfish species on Georges Banks, southern New England, and the Gulf of Maine. This bioeconomic model is used to explore how permanent marine sanctuaries on Georges Bank might affect catches, revenues, and spawning stock of principal groundfish species in New England. The simulations explore how the location of sanctuaries relative to major ports and their orientation relative to seasonal movement patterns of fish stocks impact their effectiveness and the distribution of benefits across groups of fishers from different ports. The simulation results also demonstrate that the impacts of sanctuaries can vary greatly across species, sometimes increasing yields for some while decreasing yields for others. While the specific results from the simulations reflect the characteristics of the New England groundfish fishery, the modeling methodology and some general conclusions are applicable to other fisheries.

scholarly journals Interdecadal variability in the Gulf of Maine zooplankton community, with potential impacts on fish recruitment

2005 ◽  
Vol 62 (7) ◽  
pp. 1511-1523 ◽  
Author(s):  
Andrew J. Pershing ◽  
Charles H. Greene ◽  
Jack W. Jossi ◽  
Loretta O'Brien ◽  
Jon K.T. Brodziak ◽  
...  
Keyword(s):  
Time Series ◽  
Large Scale ◽  
Gulf Of Maine ◽  
Principal Component ◽  
Trophic Levels ◽  
Interdecadal Variability ◽  
Calanus Finmarchicus ◽  
Rapid Decline ◽  
Zooplankton Abundance ◽  
The Impact

Abstract We used principal component analysis (PCA) to explore interannual changes in a time-series lasting more than 40 years of zooplankton abundance from NOAA's Continuous Plankton Recorder (CPR) survey. This analysis identified a complex of taxa, including Centropages typicus, Oithona spp., Pseudocalanus spp., and Metridia lucens that followed a common pattern of interdecadal variability characterized by a dramatic increase in these taxa around 1990, followed by a rapid decline in 2002. All of these taxa showed a large proportional increase in winter abundance between the 1980s and 1990s. These changes could be driven by increased primary productivity during winter, caused by a large-scale freshening of the Northwest Atlantic Shelf. In addition to the “community shift” mode, the analysis found a strong mode of interannual variability attributed to previously described changes in the abundance of late-stage Calanus finmarchicus. To explore the impact of these modes on higher trophic levels, we correlated the zooplankton modes with recruitment time-series from 12 fish stocks from the Gulf of Maine region. Several significant correlations were found, suggesting that the changes in the zooplankton modes may reflect broad changes in the Gulf of Maine ecosystem.

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