HUDSON STRIPED BASS

A LOOK AT HUDSON RIVER STRIPED BASS PRODUCTIVITY

Gary Caputi, Publisher, Making Waves

Could the Hudson be the savior of the Atlantic striped bass population?

The Hudson River is more important to the overall health of the total coastwide stock of striped bass than fisheries managers are willing to admit, and its long past time they make a concerted effort to better understand and account for this vibrant spawning and nursery mecca when developing stock assessments, management plans and regulatory schemes. The Hudson producer area has been the striped bass fishery’s savior in its darkest times and has grown in importance especially in light of the decline of several major spawning rivers in the Chesapeake in recent years.

I’m no fisheries biologist or stock assessment scientist, but I have been involved in fisheries management for many years and spent a lot of time listening to the experts present volumes of data in an effort to guide the regulatory decision-making process. I was a striped bass advisor to Atlantic States Marine Fishery Commission and later spent nine-years on the Mid Atlantic Fisheries Management Council representing New Jersey’s fishermen and women.

I am an avid striped bass angler. I’ve written numerous articles on the subject. I’ve fished for them from Maine to North Carolina from beach and boats, in rivers, bays, and on the open ocean. The New York Bight is my home waters and striped bass fishing there has been spectacular. I have been around stripers and fisheries management for a long time.

The instability of the Chesapeake Bay as a producer area is widely recognized, and the result of a variety of factors but the one with the greatest negative impact is the annual variability of favorable spawning conditions in its tributary rivers. The spawning variability is exacerbated by other factors like decades of overfishing, the strip mining of Chesapeake Bay’s menhaden biomass in the Virginia portion of the Bay, and the destruction of the once ubiquitous oyster population. Menhaden, in addition to being the primary food source for striped bass, play an important role in the bay ecosystem. Along with the oysters that once flourished there, they play a role in maintaining the water quality of the entire system. Combined with the negative impact of pollution, bay waters are often plagued by algae blooms and oxygen dead zones that hamper recruitment of young-of-theyear stripers. The ability to make it from larvae to fully recruited members of the spawning stock biomass (fish that have reached sexual maturity) comes up against some pretty long odds.

The Hudson has had its pollution problems in the past but much of it was alleviated in the decades following the implementation of the Clean Water Act. The river supports a world-class striped bass fishery and a healthy and growing spawning stock biomass. The expansive Hudson nursery complex is incredibly rich in varied food sources for stripers large and small. Thanks to some of the early work of the Recreational Fishing Alliance menhaden have been protected from the major sources of commercial exploitation for over two decades in New Jersey, and surrounding States followed suit. As a result, menhaden stocks have exploded creating an all you can eat buffet for striped bass.

Why is the Hudson stock flourishing when the Chesapeake stock is experiencing such wide swings in striper production? I believe it’s because the Hudson provides a more stable spawning environment year in and year out, and there is a more stable food source for stripers of all sizes to thrive.

The Young-of-the-Year Survey (YOY) used by the ASMFC to track annual striper production for the Bay and Hudson provides some useful hints about production. I find it interesting that the annual Bay YOY numbers are looked forward to with great anticipation by managers and anglers alike,

continued from page 6 but there has been little fanfare surrounding the release of the results in the Hudson, until recently. It might be because scientists believe the Hudson accounts for only 25-percent of the total coastwide spawning stock, but is that really the case?

The YOY data for the upper Chesapeake Bay is generated through sampling conducted by the Maryland DNR. The lower bay study is done by the Virginia Institute of Marine Sciences. The Hudson River YOY index is conducted by the New York DEC. It’s interesting to look at the productivity of spawning stocks in each region to determine which producer area is doing the best job of pumping out baby stripers. I looked at the most recent 35-year period of survey data (1985 through 2021) since the Hudson study didn’t begin until 1985 and the Virginia study was halted several times in the 1970s and 80s due to lack of funding. The review makes a strong case for the Hudson’s contribution to the coastwide stock being considerably larger than previously thought and explains the vibrant striper fishing it supports.

All three YOY indices include data collected in a similar manner. Handpulled beach seine nets are used to sample specific areas where striper fry can be found at the same time each year ending with a hand count of how many fry were captured. The numbers are compiled, an average number of fish per tow is calculated and used to update the dataset.

During the last 35-years, the Maryland and Virginia vary but there is one caveat. The long-term average for all the years the survey has been in existence is not the same for both states. The Chesapeake Bay complex is composed of numerous tidal rivers that stripers run up to reach freshwater to spawn. According to Chris Moore, senior research scientist with the Chesapeake Bay Foundation, cold wet springs that create strong flow rates in these feeder rivers are associated with higher degrees of spawning success. It is interesting that when the river conditions are ideal it does not take a particularly large cohort of spawning females to create an extraordinary YOY number and, in fact, some of the highest YOY’s have been generated when the spawning stock biomass was at low levels. I looked at the number of years that exhibited spawning success at or above the long-term average for each of the three areas and try to take into account the long-term average for each dataset to get an idea of overall productivity. Remember, I am simply trying to get a handle on the spawning productivity of the two major producer areas.

First let’s look at the two Chesapeake survey indices. During the 35-year time frame the Maryland YOY survey results identified 16 years where the production of young fish was at or above the long-term average of just over 11 fry per tow, and 19 years that were below the average. Of the 19 below average years, 13 came in a less than half of the long-term average indicating that spawning success was particularly disappointing.

The Virginia VIMS survey has a significantly lower long-term average of only 7 fish per tow but during the last 35-year period has been more consistently above the long-term average showing 27 years at or above average. This consistency could be because the three major spawning rivers sampled are closer to the ocean and experience stronger tides and saltwater intrusion than the Maryland portion of the Bay. That said, both Bay datasets show a fishery that has a relatively high level of variability in spawning success due to the variability of environmental spawning conditions mostly related to rainfall and warmer than typical weather conditions. Coupled with an environment that is not as rich in food sources for young fish due to wholesale menhaden exploitation and poor water quality, and you realize the odds that Chesapeake Bay hatchling will recruit to the fishery even if it manages to survive the spawning process are pretty long.

The Hudson River YOY Indices is a different story. The long-term average for the Hudson dataset is nearly double Maryland and nearly triple Virginia coming in at an impressive 19 juvenile stripers per haul. During the last 35-years Hudson spawning success surpassed the long-term average 18 times and of the remaining years 17 years the YOY came in between 11 and 18 fish per tow. The data seems to indicate the Hudson production is continued on page 8

What factors make the Hudson more productive in my judgement? It’s a large river that appears to provide a more stable spawning environment that produces a larger number of young-of-the-year. The water temperature tends to be cooler in the spring and freshwater flow is more consistent year to year due to the 13,200 square mile watershed that feeds it. The lower river experiences strong tidal influences that extend 153 miles upriver. The result of these factors is a stable, highly productive spawning area for striped bass that maintains the semi-buoyant fertilized eggs in solution for the requisite amount of time at near optimum temperatures for them to hatch. When higher young-of-the-year production is consistent, and the estuary environment is rich in forage a higher number of small fish survive to recruit to the fishery increasing the number of spawners that return to the river each spring. The stock expands, the cycle repeats.

It stands to reason that more work on the Hudson producer area’s contribution to the coastwide stock needs to be done and it seems the ASMFC agrees. The 2022 Stock Assessment Update, under the data/ research priorities section, lists the “development of an index of relative abundance for the Hudson River stock.” While that is good news, the Commission has to follow through on that key priority. With the next benchmark assessment set to occur in 2027 when biological reference points and other key measures of the health and makeup of the stock will be considered, it would be of great value to start laying the groundwork for the inclusion of an updated analysis of the two major producer areas and their relative contributions to the Atlantic Coastal Migratory Stock in the benchmark assessment.

There are other factors that make the Hudson critical to the future of striped bass. A warming ocean environment could further hamper spawning success and migration of Chesapeake Bay fish. If corresponding sea level rise takes place it could changing the face of the Bay estuary. Will there be a northward shift of striped bass as we are seeing in some other species? Will that make the Hudson even more important to the fishery? Another thing that receives little attention is what appears to be renewed spawning or greater spawning in rivers like the Delaware, Connecticut, and others considerably further north. Do they have the potential to contribute? There is so little known about these issues and so little being done to find out, but one thing is clear. The Hudson River is a critical producer area for striped bass, and it deserves the attention of everyone involved in striped bass management and the scientific community.