Through the looking glass

The National Environmental Education Foundation (NEEF), in Washington, D.C., states that “. . . the average sea-surface temperature has been consistently higher during the past three decades than at any other time since reliable records began in 1880.” Chart courtesy NEEF

By Capt. Jerry Morgan
For Points East

With changing times come transformations that affect all facets of life. Some occur as major events, while others are hardly noticeable, even as decades slip by. It is only when someone reflects back in time and recalls something to that effect – “I remember when frostfish were cast onto the shores of Long Island Sound” – that the pieces fall together. Suddenly, the realization sets in when someone else asks, “What are frostfish?”

Here in the sound, there are no longer any frostfish to gather during the cold season. They are a thing of the past. We always referred to these fish as “frostfish,” but they are actually whiting or silver hake. Within that group, tomcod is often included. Normally deep-water fish, these species, during cold winter nights, would migrate close to shore from the continental shelf. There, they would chase sand eels and the like right up to the shore, often beaching themselves in the process. When this phenomenon occurred, coastal folks would walk the surf line, picking up these fresh, near-frozen fish for the table. Thus, the name “frostfish.” Long Island Sound has lost, at least for now, this valuable resource as well as a centuries-old tradition.

Frostfish. Photo courtesy Capt. Jerry Morgan.

The health benefits of these North Atlantic cold-water fish are extensive. They are packed with all sorts of nutrients, minerals, vitamins, lipids and amino acids – B12, phosphorus, vitamin B, niacin, magnesium, calcium, and the like. Scanning a checklist of their benefits recalls the wild “snake-oil” claims of the 1800s. According to “Fish Facts of Health Benefit Times,” the meat of these fish helps form DNA, lower fatigue, enhance bone health and development, support digestion, lower cholesterol, help to treat cramps, benefit the heart, and so on. The only difference between frostfish and snake-oil remedies is that, today, these claims are substantiated.

From then to now – perhaps even further back in time – we have seen similar events occur. Our tinker mackerel headed north, as did much of our lobster population. But why? As a sport fisherman over many decades, it is obvious to me that fish populations are dwindling. It is also evident to me that fisheries management, as sophisticated and advanced the methods have become, cannot stop change; it can only attempt to effectively manage its result.

All along the Atlantic coast, change is occurring. And when one sector experiences a decline in a species, another often becomes a benefactor. For example, the waters of the Delmarva (Delaware, Maryland and Virginia) Peninsula have seen a gradual decline in their black sea bass (Centropristis striata) population. At the same time, Long Island Sound is experiencing an emergence of that fishery, which is becoming established and populating. According to NOAA (National Oceanic and Atmospheric Administration), collectively, this species is not overfished. However, there definitely appears to be a geographical shift to the north in their biomass.

Fish habitat is changing. As with humans, over a period of time fish can only adapt so much. They need a compatible habitat that must include ample forage, relatively clean oxygenated water, and a temperature range suitable for maintaining life’s functions. Other factors – such as predation or overfishing, which can negatively affect an otherwise sustainable fish population – may also figure into a fish stock being depleted or even collapsing.

It’s simple. When critical habitat changes, or is altered in such a way so as to potentially create a life crisis, fish either move on to a more compatible habitat or succumb to the pressures.

We hear a lot of talk, read extensive scientific reports, and are subjected to a never-ending stream of hype concerning climate change. The conversation and debate rages on: Are conditions part of a cycle that will correct itself? Or are we trending toward warmer waters? Long-term historical documentation – with records dating back to the 1880s, published by a Long Island Sound Study – surely points to the latter phenomenon.

Graph 1 uses mean winter water temperatures to illustrate that pattern. Since coastal water temperatures fluctuate more during summer and fall, winter temperatures were used because of less fluctuation, thereby rendering a more accurate result.

Note that long-term water temperatures were graphically illustrated and plotted from approximately 1890 to 2020 in Celsius degrees, not Fahrenheit (1ºC = 33ºF/10ºC = 50ºF). Temperatures are color-coded to reflect those at Woods Hole, Mass.; and Milford, Noank and Niantic Bay, in Connecticut.

Looking at Milford, just west of New Haven, one can see that, in 1962, those long-term inshore winter water temperatures were tagged at 33.8ºF and have risen in 2020 to 39.2ºF. Allowing for seasonal fluctuations, this study clearly indicates a warming trend, and hints to why Long Island Sound is losing its cold-water species to the north. It also suggests why southern Atlantic species are migrating from even warmer waters to the cooler ones of the sound and beyond.

If we look further to Graph 2, a NOAA graphic of mean daily average air temperatures, we can see that the Delmarva coastal region averages from 55.1ºF to 60.0ºF, and that Long Island Sound averages from 50.1ºF to 55ºF. Even though both of these regions have seen an increase in coastwise water temperatures over the years, as well as in air temperatures, the sound remains cooler. This phenomenon alone lends further credence as to why certain fish species are moving from less-tolerable, warmer waters into cooler habitat-friendly environments.

Case in point: Today, it is not unusual for South Atlantic gray triggerfish (Balistes capriscus) or ladyfish (Elops saurus) to be hooked in Long Island Sound. And lately, catches of redfish or red drum (Sciaenops ocellatus) and Spanish mackerel (Scomberomorus maculatus) have been recorded in increasing numbers.

Here in the Northeast, we are conditioned to daylight saving time. On longer days, there is more time to fish. When standard time takes over, days become shorter. As each season passes, they seem to meld together, and the slight changes in temperature become imperceptible to the average angler. However, over a period of time, these changes mount up until one day we take notice – similar to noticing a new building suddenly appearing on a route well-traveled.

Unless frequently referring to a detailed log, a fisherman will hardly notice a change in a fraction of a degree or, for that matter, if a change even occurred or is occurring. What will be noticed is a transformation in the fishery, such as an unusual catch or, more drastically, no catch at all. Consistently fishing in familiar waters can reveal such a shift, but if one explores new waters, or travels to distant locations to target other species, only conversations with knowledgeable locals will unveil secrets of their fishery.

There is a big difference whether declining numbers of a fish species are due to warming waters and migration or removals of any kind. The impact of a species declining due to warming waters will be vastly different from a decline in numbers because of habitat loss.

In the former case, overall biomass is not necessarily affected. In the latter, it is. Fish will continue to move until they find a hospitable home. If one cannot be found along the coast, various species will be forced to seek deeper water where they will encounter other challenges.

When seawater warms, there are other considerations to take into account. Evaporation is one of those ways Mother Nature seeks to moderate its ocean temperatures. Similar to a human function, evaporation will cool down surface water, but only to an extent. Depending on water depth, that could increase salinity, thereby altering the habitat and forcing fish to once again adjust to conditions.

In early spring, when Long Island Sound receives cold, fresh water from upland waterways, its salinity will be down, especially at the eastern end. This is what returning salmon key into when heading upriver, and what keeps the great white sharks out. As spring rolls into summer, temperatures rise and evaporation occurs, increasing the salinity to the point of equaling that of the Atlantic. That is what brings certain forage and predator species following the coast and Gulf Stream into the sound.

Globally, there is a trend toward warming sea-surface water temperatures (Graph 3). According to NOAA’s National Data Buoy Center, Atlantic sea-surface temperatures during the warmest months (August through October) warmed 2º to 4ºF in the last 30 years. Keeping pace, the Gulf of Mexico buoys analyzed show an increase in warming of 1º to 2ºF in the last 40 years. Overall, large swaths of global oceans have warmed 1º to 3ºF during the last century.

It is also noted that the National Environmental Education Foundation (NEEF), in Washington, D.C., states that “. . . the average sea-surface temperature has been consistently higher during the past three decades than at any other time since reliable records began in 1880.” See Graph 4.

As we can see, this trend has been going on for quite some time, and if any reversal is to occur, it will not happen overnight. Until then, anglers will continue to fish and notice subtle, or not so subtle, variations in their catches as fisheries managers do their best to uphold the Magnuson-Stevens Fishery Conservation and Management Act. Cetologists will document shifts in whale, dolphin and porpoise populations. Ornithologists will continue to notice changes in bird populations, and so on, while average folks just sit back and wonder why.

What will the next several decades bring? I imagine that will be determined by what section of the very long roller-coaster ride we are traveling through. In November 2019, we experienced an Arctic blast that delivered record-breaking air temperatures 30º below the norm. Those frigid single digits, coupled with gale winds, were numbing. The weather did moderate, but that was a very cold and wet period. These conditions do not, in themselves, invalidate a warming trend, but rather, perhaps, represent a hiccup in a possible transition to one.

Churning up tidal, coastal and sea waters is a healthy occurrence. It energizes the water column by releasing warmth, infusing oxygen, stirring up and cleansing the bottom, and reducing harmful sedimentation. In short, it breathes life into an otherwise devitalized-looking body of water by, in part, facilitating sediment respiration.

On the other hand, without weather fluctuations, there can be a substantial negative impact. Warmth and excessive organic debris can create a stagnant condition that results in what is often referred to as a “black-mayonnaise” bottom effect. This stifles growth – and life itself. When too much nitrogen-rich organic matter sinks to the bottom, decays, and creates this muck, an anoxic (reduced dissolved oxygen) event occurs that releases hydrogen sulfide, a colorless gas, in the process. This reaction can be extremely detrimental to marine life, and it occurs more readily as water temperatures warm.

We cannot dispute that our waters are changing, and that they are warmer than previously experienced. This will be especially evident with the strikingly unseasonably warm winter we’ve just had. Statistics from the 1880s through the present-day show this is happening, and occurring at a faster rate than over the last few decades.

Meanwhile, all of us concerned with these gradual transformations will keep a close eye on our fisheries, monitoring their migrations as well as changes to their biomass densities and conditions critical to their habitat.

Capt. Jerry Morgan is from Madison, Conn. Though he fishes from cold northern waters south to the tropical islands and beyond, he’s most at home on Long Island Sound. A board member on several fishery commissions, he’s also an outdoor writer, radio personality, blogger, photographer, outfitter and conservationist.