And here is a typical scare piece on the movement of Maine lobsters to more northerly waters.
In my opinion, Ted Cruz has demonstrated a pretty sound understanding of the climate change issues, even though he clearly does not accept the popular alarmism and questions the magnitude of the role humans play in climate change. Note that this does not necessarily deny that climate changes nor does it mean it hasn't gotten warmer over time. This is basically my attitude, and the issue of lobsters (about which I know very little) got me thinking about why I remain a skeptic. The following is a contemplation of my journey so far.
I grew up in Southern California and was an avid fisherman (sorry, no politically correct "angler" or "fisher" here). During junior high and high school (I graduated in 1969) I fished the ocean around Long Beach and Huntington Beach extensively. I was very happy with this, because I had moved to Southern California from what Californian's call the "Central Coast" in 1966; ocean fishing up there was pretty unremarkable for pier fishing at least. But the fishing in Southern California, according to the locals, had gotten pretty bad since the sardines left. At the time, I don't think anyone really know why the sardines had been replaced by anchovies, though I think over harvest was assumed to some extent (commercial harvest of Pacific sardines is an important industry). At any rate, many of the really desirable pelagic gamefish like yellowtail (Seriola lalandi dorsalis) had moved south and/or away from the coast. For me, the most important pelagic gamefish I could catch was bonito (Sarda chiliensis lineolata); they are great fun to catch on light tackle, but relatively small.
I moved out of California in 1978 seeking fame and fortune in the great Pacific Northwest. I don't know when it was exactly, mid-1980s probably, that I realized the better gamefish had returned to Southern California and so had the sardines. Turns out there was a climate connection, namely the the Pacific Decadal Oscillation, or PDO (a summary of sardine-anchovy and related ocean changes can be seen here).
I was, of coursed, "bummed" that better fishing was afoot in my old stomping grounds, but by the 1980s I was firmly entrenched in what, to me, was practically Heaven on earth: The great and wonderfully backward* state of Idaho. And Idaho had salmon; a few remained anyway as their numbers had become perilously low. The problems with Pacific salmon are complex, but like sardines, salmon are an important commercial resource; however, they are themselves a top predator and sought-after game fish. And like anchovies and sardines, they are affected by the PDO.
In fact, the PDO was more or less discovered by researchers studying salmon catches in Alaska and the Pacific Northwest. Despite the many threats Idaho salmon face as the outmigrate and return to spawning streams in the Columbia River Basin (CRB; something I talked a little about in a previous post), the PDO revealed a pattern of relatively higher salmon catches in Alaska and lower catches farther south in the Pacific Northwest; these trends reverse when the PDO phase shifts, though the southern population patterns may be somewhat less to connected to the PDO than in Alaska. Regardless, there are also effects on precipitation and streamflow. I've merged two graphs here that, while the relationship is imprecise, clearly suggest it:
The El Nińo-Southern Oscillation (ENSO) is a smaller period pattern (or sub-pattern) overlaid on the PDO that more directly affects annual precipitation, so a precise relationship to PDO cannot be expected.
And Chinook salmon were relatively abundant in the early 2000s in Idaho. Idaho's South Fork Salmon River (SFSR) is one of the premier anadromous salmon spawning streams in the interior CRB. There are no dams on the Salmon River, so fish returning from the ocean are relatively unimpeded once the reach Lewiston, Idaho. There is also a program for supplementing the wild Chinook salmon population with hatchery juveniles reared at Idaho Fish and Game's (IDGF) McCall Hatchery. But here's a graphic I made for a presentation that shows redd (spawning "nests") recorded at IDFG's index areas on the SFSR:
The increase in salmon allowed IDFG to establish a summer Chinook salmon fishing season when more hatchery salmon than needed for the supplementation program returned and were collected. I don't have figures at hand, but I think the angler harvest was about 6,000 fish in 2001 and 2002; it has declined some in recent years.
Presently, linking the PDO to SFSR salmon is sketchy and should be considered hypothetical pending longer term study. Ocean conditions are undoubtedly important to salmon production and there seems to be some uptick in fish during the cool PDO period starting in the late 1990s; but the CRB fishery has been historically devastated by development of the Columbia River Hydrosystem, which has completely altered the river's ecosystems, commercial, recreational, and subsistence fishing, irrigation diversions, riverine habitat changes, climate change according to some, and so forth. Conversely, salmon populations in the SFSR are being supplemented with hatchery production and this seems to be helping keep populations relatively robust. In addition, in the case of salmon we are not specifically considerating a shift in species range as much as subpopulations being deferentially affected by changes in ocean conditions in feeding areas.
So what about lobsters? There is a similar ocean pattern in the Atlantic called the "Atlantic Multidecadal Oscillation" (AMO) that has been linked to changes in faunal distributions. The authors of this recent paper say this (possibly about fish in particular):
Could this include lobsters? I don't see why not, though demersal organisms of limited mobility would not be expected to change their ranges as quickly quickly as fish. But if you look, it's not too hard to see similar variability in lobster catches in Maine, which, interestingly, seem to be increasing."During positive phases of the AMO there is generally a poleward shift in the distributions of marine organisms and a subsequent equatorial shift during negative phases."
The above discusses fluctuations in animal distributions related to climate cycles. Other fluctuations also occur in nature. For example, my graduate study was expected to focus on dispersal in microtine rodents, a group widely known for cycles in population density; lemmings and voles are familiar examples. I'm no longer up to date on this phenomenon, but I believe that the cycling is still not understood and is seemingly endogenous, but there may be somewhat synchronous effects on predator populations. Snowshoe hares (Lepus americanus) are another species with somewhat longer population cycles, and I think these may affect predator abundance and distribution in some marginal areas like central Idaho.
For me, the take home message is that nothing in nature is static and cyclic phenomena are common. While cyclic animal populations may be quite obvious because of irruptions, longer period oscillations may be less obvious. Something like "normalcy" for climate or animal distributions may intuitively seem reasonable, but perhaps only insofar has humans have difficulty seeing patterns that are long relative to their lifespans (that is, human lifespans may only be long enough to witness one or two phase changes in natural multidecadal oscillations). So I philosophically embrace variability; nature is unconstrained by what we want it to be. Are things getting worse? Maybe; maybe we need more time to find out. Change happens, it need not be feared; if it's deleterious, adapt and mitigate. I choose to remain optimistic and, as always in later life, to be skeptical of all assertions about how nature "should" behave.
__________
* I say this in a non-pejorative sense: Idaho was very much the embodiment of social and environmental conditions that I was distressed to see vanishing in California as it became increasingly overcrowded.
