STRIPED BASS: WISHFUL THINKING WON'T MAKE THINGS RIGHT

It’s a refrain that I’ve heard more and more over the past year:  “Yes, striped bass recruitment in the Chesapeake Bay might be tanking, but as the climate gets warmer, the Hudson River is taking up the slack.”

The people saying such things tend to fish somewhere in or around the New York Bight, or know anglers who do, and tend to point to recent years’ fast early spring fishing in Raritan Bay, and last year’s strong end to the season in the New York Bight, as evidence that the center of striped bass recruitment might be shifting north.

The most recent example of such thinking was an article titled “Where have the striped bass gone?,” which appeared in the Cape Gazette, a Delaware news source.  The article read, in part,

“Today, there is another drop in the young of the year numbers in the Chesapeake Bay.  The reason for this drop may have more to do with global warming than anything else.

“My friend…describes the number of striped bass in the Raritan River and its tributaries as tremendous.  He has records that include fish to 25 pounds that were available all the way up to New Brunswick [New Jersey].  [He] has fished this region for 40 years, and this is the best action he has ever seen.

“I have other friends who run charters on Raritan Bay, and they carry two parties a day.  They look for breaking fish feeding on huge schools of menhaden and then cast to them.  Most anglers use plugs or bucktails, but fly fishermen also do well.  My son…gets in on the action trolling plugs from his kayak.

“[My friend] believed the scientific world needs to look at the young of the year numbers from the Hudson River stock.  With more and more females moving into the Hudson and its tributaries, such as the Raritan River, he thinks, and I agree, that river system has got to be producing a substantial number of young of the year striped bass.

“So why are these females moving from the Chesapeake Bay to the Hudson River?  Could it be that the ocean is becoming warmer than they like and they prefer cooler water farther to the north?  I have no idea, but I do know we are catching warm-water fish in Delaware that we never caught before…”

It’s a nice theory, and it even makes some logical sense, as the ocean is certainly warming, and fishes are extending their range farther north.

It’s such a nice theory, that it’s almost too bad that it’s wrong.  But facts must be given their due.

We can begin by debunking the notion that there are “more and more females moving into the Hudson and its tributaries,” and all of “these females moving from the Chesapeake Bay to the Hudson River,” for not only is there no science suggesting such movement, but there is recent research demonstrating that such movement of fish from the Chesapeake to the Hudson just isn’t happening.

Back in 2020, the Massachusetts Division of Marine Fisheries released the results of a coastwide study, which found that there are six genetically distinct spawning populations of striped bass (leaving aside the non-migratory, local populations that exist in some southeastern states’ rivers).  Three of those populations spawn in Canadian waters, three in the waters of the United States.  Of the populations that spawn in the US, one is unique to the Hudson River (and to the Kennebec River in Maine, where Hudson-stock fish were transplanted a few decades ago), one is unique to the Chesapeake Bay and Delaware River (the original Delaware population probably having been extirpated as a result of pollution during the 20^th Century, and then replaced by Chesapeake fish colonizing the Delaware spawning reaches after travelling through the Chesapeake and Delaware Canal), and one unique Roanoke and Cape Fear rivers in North Carolina.

Note that the genetic markers used to differentiate the different spawning populations truly are unique.  Ben Gahagan, the Massachusetts biologist spearheading the project, noted that

“For a given striper, we are able to determine the group it belongs to with 99 percent accuracy.”

The hope is that such ability will eventually allow biologists to manage individual striped bass spawning stocks, adopting management measures appropriate to each stock’s condition, rather than managing all striped bass on the coast as a single unit.

But the immediate upshot is that all striped bass clearly do not form a single, fungible unit; a female from the Chesapeake Bay belongs to a population distinct from females in the Hudson River, and is not going to abandon her ancestral home waters for cooler seas when the Chesapeake begins to warm.

Having said that, warming waters may very well be having a negative impact on striped bass reproduction in the Chesapeake Bay.  Scientists have determined that weather-driven conditions in spawning rivers determines the success of the Chesapeake striped bass spawn.  A cool winter and cool, wet spring tend to support strong recruitment, while a warm winter and warm, dry spring can lead to recruitment failure. 

Climate change may very well be stacking the deck against the Chesapeake’s striped bass, but that doesn’t mean that the Hudson River is taking up the slack.

The New York State Department of Environmental Conservation has published a chart of the Hudson River striped bass juvenile abundance index that dates back to 1985.  While a precise value is not given for each year, the chart does show how each year’s juvenile abundance index compares with both the long-term average and with the 25^th percentile of the time series, which is used to determine the need for management action under the Atlantic States Marine Fisheries Commission’s striped bass management plan.

If we look at the indices in 5-year intervals beginning in 1988 (leaving off the earliest three years just to make the data more convenient to handle), this is what we find:

·        In the first five-year interval, 1988-1992, the JAI was above the long-term average three times, and below the 25^th percentile once.  The highest juvenile abundance index for the entire 37-year time series occurred in 1988.

·        In the second interval, 1993-1997, the JAI was again above the long-term average three times, just about equal to the long-term average once, and very slightly above the 25^th percentile once.

·        In the third interval, 1998-2002, the JAI was above the long-term average twice and below the 25^th percentile once.

·        In the fourth interval, 2003-2007, the JAI was above the long-term average twice, below the 25^th percentile twice, and just about equal to the 25^th percentile once.  The second-highest JAI in the 37-year time series occurred in 2007.

·        In the fifth interval, 2008-2012, the JAI was above the long-term average once and just about equal to such average on another occasion, below the 25^th percentile once and just slightly above such percentile in another year.

·        In the sixth interval, 2013-2017, the JAI was above the long-term average twice and below the 25^th percentile twice, with the third-lowest JAI in the 37-year time series occurring in 2013 (the lowest and second-lowest JAIs occurred in 1985 and 1986, respectively).

·        Finally, in the seventh interval, 2018-2022, the JAI rose above the long-term average twice and just about equaled that average on another occasion, while falling below the 25^th percentile once.

Just what does all of that information tell us?

First, it tells us that there is no big spike in Hudson River striped bass recruitment in recent years. 

Striped bass recruitment in the Hudson River is very irregular, with above-average years often adjacent to years when recruitment falls below the 25^th percentile of the time series.  Sometimes, annual spikes in Hudson River recruitment align with those in the Chesapeake Bay; that happened in 2021, 2023, and 2015, but it did not happen in 1996 nor in 2011, when Chesapeake recruitment was very strong, but Hudson River recruitment was at or near the 25^th percentile level.

If anything, Hudson River recruitment is, on average, lower than it was 30 or so years ago.  The Hudson produced four consecutive above-average year classes in 1987, 1988, 1989, and 1990, with the 1988 year class the largest in the time series.  The river hasn’t produced four consecutive above-average year classes since, and has produced two consecutive above-average year classes on only two occasions, once in 1993-1994 and again in 2014-2015; on both of those occasions, the JAIs rose only modestly above the long-term average, never reaching the level of even the smallest year class produced between 1987 and 1990.

If anything, Hudson River striped bass production has been on a declining long-term trend, and not increasing as some have suggested.

So why has fishing been so good in Raritan Bay over the past few years, and why was the end of the season so hot in the New York Bight?

The answer can be found by examining the occasions, over the last 20 years or so, when big year classes were produced, both in the Hudson River and in the Chesapeake Bay. 

The Maryland section of Chesapeake Bay produced a very large year class in 2001, and other smaller, but still strong, year classes in 2003, 2011, and 2015.   The Hudson River produced a very strong year class in 2007, strong year classes in 2001 and 2003, and slightly smaller, but still well above-average, year classes in 2010 and 2014 (although the 2020 year class was also very strong, the resulting fish are still too small to be relevant to this discussion).

The spring striped bass fishery in Raritan Bay appears to occur largely at the expense of females staging there before ascending the Hudson River to spawn.  Given that a 50-pound striped bass is approximately 20 years old, the above-average 2001 and 2003 year classes from the Hudson River can easily account for the very large bass caught in Raritan Bay in recent years, while the 2007s and 2010s make up the mid-sized fish and the 2014s constitute bass that have recently entered the 28- to 35-inch slot.

The end of last year’s fall run saw the same Hudson River fish joined by 2001s, 2003s, 2011s, and 2015s from the Chesapeake Bay, to provide spectacular fishing in the New York Bight. 

It's not necessary to make up theories about female bass from the Chesapeake suddenly migrating to the Hudson River to spawn to explain the good fishing.

It’s not necessary to imagine a suddenly more productive Hudson River, when the data clearly says otherwise.

But it is necessary to take action to protect the Chesapeake Bay's striped bass population.  It’s currently overfished, recruitment has been chronically low, and a spike in 2022recreational landings threatens to cripple its chance at rebuilding.

Wishful thinking about the Hudson River isn’t going to change those facts.  Only timely, concerted, and decisive action stands a chance of making things right.