Gary Nelson, Jennifer Stritzel Thomson, Paul Caruso, John Boardman
> Striped Bass Monitoring Reports
Massachusetts is currently home to the largest recreational
striped bass fishery in the country. Our total catch of stripers
in 2000 alone approached 7.1 million fish. High population
abundance of striped bass, the diversity of the Commonwealth's
nearshore habitat and many sources of food for stripers are
major factors contributing to the success of this fishery.
Without a doubt, striped bass are the backbone of our recreational
industry and provide enjoyment to hundreds of thousands of
recreational anglers each year. Accordingly, we give this
important resource a high level of attention by conducting
many special investigations and monitoring programs designed
to support the regional planning process.
Figure 1. Proposed sampling of
Sound for 2006
In 2006, we conducted a special study to examine the temperature preferences of striped bass during their summer residence. The thermal preferences of striped bass had been described for landlocked populations, but it was unknown if such preferences exist for striped bass in the continuously changing marine environment.
The questions asked were:
- What temperatures are experienced by striped bass?
- To what extent does the environment influence the temperatures?
- Do striped bass exhibit any temperature preferences or detectable behavioral patterns (e.g., day/night differences)?
To determine if striped bass exhibit a preference, temperature in the environment and temperature experienced by individual striped bass was measured and compared. If striped bass experience similar temperature ranges that are available in the environment, they probably have no preference, but if they experience a smaller range in temperature, it would suggest a preference.
The focus of the study in 2006 was Salem Sound, Massachusetts (Figure 1). Monitoring buoys were placed at 15 sites and temperature was recorded every 2 hours at various depths in the water column. Striped bass were captured, tagged with a temperature-recording logging tag (Figure 2) and released. The tag recorded temperature every 2 hours.
Figure 2. A 30" bass with the implanted temperature-recording logger tag and backing tag
In total, 24 of the 151 striped bass tagged in June 2006 were recaptured by recreational and commercial anglers in the intervening year. Release sizes of recaptured fish ranged from 21” to 33” total length and fish were at-large from 1 to 351 days (median = 23 days). Most tagged fish (22) were recaptured during June-August 2006 generally <5 nm from the release location. Results reveal that striped bass experienced a wide range of temperatures while at-large during June-August 2006. The temperatures experienced by striped bass ranged from a low of 7.0 (44° F) to a high of 28.5°C (83°F), but most observations (95%) were between 10°C (50°F) and 25.5°C (78°F). Average temperatures while at-large ranged from 15.0°C (59°F) to 22.2°C (72°F). In comparison, the coldest temperature measured at the twelve stations was 6°C (43°F) at 36.5 meters (120 feet) and the warmest temperature measured was 25°C (77°F) at 0.6 meters (2 feet). No day-night differences in temperature preferences were detected. Comparisons of water depth-temperatures versus striped bass temperatures showed that most striped bass stay in temperatures above 9-10oC (48-50°F), generally found in depths <10 m (30 feet), even though colder temperatures are available. Since they do not appear to go below ten meters due to cold water, striped bass probably forage on benthic prey only when near-shore. Therefore, any impact on economically-important prey like the American lobster may be concentrated to specific shallow-water areas.
Nelson, G. A., M. P. Armstrong, J. Stritzel-Thomson, and K. D. Friedland. 2010. Thermal habitat of striped bass (Morone saxatilis) in coastal waters of northern Massachusetts, USA, during summer. Fisheries Oceanography 19: 370-381. [link to abstract - contact Gary Nelson for reprint]
Age and Growth Sampling
1 year Growth Mark
Atlantic coast states that harvest striped bass are required,
as part of the interstate management process, to characterize
their landings. Monitoring of age, size, and sex composition
of both commercial and recreational catch and landings of
striped bass is indispensable for identifying the need for
constructive revisions to management strategies and for confirming
estimates of population parameters. In Massachusetts, we conduct
annual sampling of the commercial harvest at seafood dealerships.
Information collected from more than 9,500 stripers beginning
in 1982 include length, weight, sex and scales from each fish
examined. We also conduct annual sampling of the recreational
harvest at several striped bass tournaments. In 2001, we solicited
volunteer recreational anglers to collect scales from harvested
and released fish to boost our sampling coverage. We can observe
annual "growth rings" on fish scales and use them
to estimate age composition of the catches and rate of growth.
Anchor tag being inserted
into striped bass before being released
Tagging and long-term monitoring of tag recoveries improves
understanding of distribution of and movement of Atlantic
striped bass stocks and generates vital information about
annual survival rates. A state-federal cooperative study,
now the largest of its kind, has applied tags to more than
370,000 wild and hatchery striped bass since 1985. Massachusetts
DMF began a striped bass tagging study in 1991 as part of
this ongoing state-federal cooperative effort and has tagged
and released over 5,000 fishes. We employ skilled charterboat
captains to guide and collect fish from shoal feedings grounds
around Cape Cod. Our study furnishes the largest proportion
of legal-size fish to this overall effort. Striped bass tagged
in Massachusetts' waters have been recaptured as far north
as New Brunswick, Canada and as far south as Georgia, USA.
Striped Bass Diet and Bioenergetics
> Food Habits of Striped Bass in Coastal Waters of Massachusetts
> Nelson, G. A., B. C. Chase, and J. D. Stockwell. 2006. Population consumption of fish and invertebrate prey by striped bass (Morone saxatilis) from coastal waters of Northern Massachusetts, USA. J. Northw. Atl. Fish. Sci., 36: 111–126. (674 Kb)
MarineFisheries conducted a study during 1997-2000
to address the issues of forage needs of the recovered striped
bass population and the potential impacts of striped bass
consumption on economically important prey species. This DMF
research project was designed to provide diet information
of striped bass and to build a computer-based bioenergetic
model that allows us to estimate consumption rates of striped
bass for any particular food item, such as river herring,
menhaden, and even the commercially- important lobster. We
collected diet information from over 3,000 striped bass collected
from the North Shore, Cape Cod Bay, and Nantucket Sound regions
of Massachusetts. Some findings of the study are summarized
We found that, in general, striped bass consumed mostly fish
(menhaden, herring, silversides, and sand lance) and invertebrates
(crabs, sand shrimp, and sea fleas); however, the amounts
eaten varied depending on the month of summer, fish length,
and where the striped bass were captured. Large bass (>24
inches) generally ate more invertebrates (mainly lobsters
and crabs) than small bass (<24 inches), but small bass
ate more fish (mainly menhaden during August-September) than
large bass. Striped bass captured from rocky shorelines or
offshore waters generally ate more invertebrates than bass
captured from estuaries or harbors.
Striped Bass gut contents
displaying different sizes of prey
We also found that the striped bass ate different sizes of
prey. Fish prey ranged in size from 0.9" to 19"
total length, and crab prey ranged in size from 0.1"
to 4" carapace width. Individuals of menhaden and sand
lance were generally <5" and the three dominant crabs
(rock, green, and lady crabs) were generally <3".
American lobsters eaten by striped bass were <2" carapace
Using the bioenergetic model, we estimated that an "average"
striped bass of six years (27 inches in length) must eat about
16 pounds of prey to gain 1 pound in weight during June-September
in Massachusetts' waters. Most energy contributing to the
growth of this age class comes from different fish prey during
June-July, but mainly from menhaden during August-September.
These results confirmed the importance of fishes like menhaden
to the survival and health of the striped bass population.
(see Graph of Consumption below)