fisheries
...real risk of being counterproductive and it can therefore not be recommended by scientists. (I have made this argument before, based on a cod food shortage resulting from a systemic fertility decline. But it works either way: cod starved by “too many herring” or cod starved in a generally starving ocean…in either case, killing seals can be expected to worsen the starving fish problem.) What if DFO is right? If there has been a great explosion in the growth and abundance of herring and other small pelagic fish, then how do these fish “limit the flux of nutrients to the benthos?” It is difficult to imagine the dynamics of the ecosystem as DFO now describes it. How did the bottom fish in decades and centuries past ensure that energy flowed to the bottom? Was this done by lots of big cod always eating lots of herring? By keeping the potentially dangerous herring biomass cropped down? Instead of an ocean with a large swimming biomass tied up in mature groundfish who maintained control over the herring, do we now have an ocean where the bulk of fish biomass is tied up instead in a lot of herring, who have reached such a level of dominance that they can now effectively keep food away from groundfish? Does this accurately describe the "transition" that has occurred in the Eastern Scotian Shelf ecosystem? In the absence of the big cod, as we see today, how do the herring manage to prevent food from sinking to the bottom (because any sinking organic bits will add energy to the bottom system, not just pieces big enough for cod to eat)? DFO seems to be suggesting that a 100-fold (or greater) increase in herrings is now intercepting, eating and hoarding all of the newly formed ocean food (plankton), plus they are consuming a dangerously high fraction of the floating fish eggs released by the groundfish. However, herring cannot effectively “juggle” the general seafood resource and retain it at higher levels in the water column, because food flows naturally to the bottom from herring. One pathway for this downward food “flux” can be seen in sinking herring eggs. Unlike the majority of ocean fish, including cod and other bottom fish, that release buoyant free-floating eggs, the eggs of herring, capelin and sand lance sink to the bottom and stick to whatever they touch. Just the shower of spawn that settles to the bottom from today’s small pelagic fish outweighs yesterday’s entire small pelagic stock biomass (if DFO is right). A 100-fold increase in herring biomass implies a 100-fold increase in the quantity of food they deliver to the sea bottom in the form of eggs. Consider that 10% by weight of adult herring is released annually as their spawn (in reality, this fraction can be higher than 10%, but for the sake of round numbers I will use 10. Also, this 10% of the live herring by weight represents more than 10% of their total food value, since fish roe is more protein-dense and calorie-rich than the fish that produces it – but again, to keep it simple, I will assume that roe represents 10% of the food locked up in herring.) Herring mature at a three or four years of age and some have been estimated to live for up to 20 years, spawning each year. Some herring spawn in spring and others in fall. Sticky sunken herring eggs then become a food that is available to virtually every type of bottom fish and other benthic animal, from large groundfish to tiny invertebrates. The flow of herring-derived food to the sea bottom today, approximately 10% of the adult herring biomass, must therefore now be about ten times greater than was the entire herring biomass pre-groundfish collapse…if herring have increased 100-fold. Fewer groundfish today (less than 10% of previous numbers) are now starving on a sea-bottom that is receiving a 100-fold increase in herring spawn, with the food value of these fish eggs being greater than the entire previously existing herring biomass, that was thought to exist during the days of better groundfish growth…can we really believe that the starvation of bottom life is occurring today due to the effects of herring? The hypothesis seems to become untenable, not least because “biomass” estimates of anything do not reveal the rate of energy flow, whether of plankton, pelagic fish, or groundfish… The casual observer might simply wonder why the starving cod do not swim up a bit and eat some of the overabundant herring. And that is a good question too… Food and energy in the ocean cannot be tied up and sequestered away from the hungry cod by the herring. Besides paying a tithe to the bottom life in the form of their eggs, herring frequent the upper parts of the seawater column, where they excrete a bodily waste, ammonium, that acts as a fertilizer to stimulate greater plant growth. Herring eat plankton, but they also “regenerate” this fertilizer in parts of the water that are affected by sunlight, and therefore herring naturally induce greater plankton growth. Some portion of this additional food will inevitably sink and contribute to the energy flow to the bottom. The nature of the disconnect between cod and herring, the “benthic pelagic decoupling” that DFO scientists are struggling to understand on the Eastern Scotian Shelf, cannot be clearly delineated and explicitly stated, because this is not a real possibility for these fish species that have long co-existed in the sea. That is not the nature of what is happening now, nor has it ever been before. What if the herring are not there? If herring are not dominating the coastal ocean and preventing the flux of energy to the bottom, then an energy poor bottom suggests the possibility of an energy poor ecosystem throughout, a "starving ocean." And this is a far more serious development. My stance on the herring question is that the dramatic biomass increase estimated by DFO most likely represents mainly an error in their assessment technique. My criticisms were detailed in an earlier article. Essentially, the flaw in DFO’s calculation has resulted from estimating the abundance of herring-type fish living at higher levels in the water column only by examining those that were caught in a bottom trawl. The apparent increase in herring biomass may be related to a shift in herring distribution and “catchability” by the bottom trawl, rather than to a genuine substantial increase in herring numbers. (See: baitfish error.) Included as evidence of the increase in herring biomass is a mention of the development of a new herring fishery on the Scotian Shelf: “Current pelagic biomass estimates are approximately two orders of magnitude higher than those of the 1970s. This is attributable primarily to the increased abundance of herring (Clupea harengus) in the west, capelin (Mallotus villosus) in the east, and sandlance (Ammodytes dubius) throughout. These increases in abundance were accompanied by the development of a large offshore herring fishery on the outer banks of the central Scotian Shelf where none had existed before 1996 (DFO 2003).” (Choi et al., 2004) The last statement is potentially misleading on two counts. First, what is a “large” herring fishery? The herring fishery that developed on the offshore Scotian Shelf post-1996 has never approximated the catches made by the Nova Scotia inshore herring fishery. In its first few years, this offshore fishery netted about 12,000 tons of herring yearly, but catches declined after 2000, dwindling to less than 1000 tons in 2003 (DFO, 2004b). In comparison, the Nova Scotia inshore herring fishery has recently landed about 90,000 tons per year. This new offshore herring fishery has also never met catch levels that were made previously in the same area, because “a foreign fishery during the period 1963-1973 is estimated to have removed as much as 60,000t in a single year from the offshore Scotian Shelf banks” (DFO, 2000). (CJFAS peer reviewers appear to have missed this factual inaccuracy in the article by Choi et. al.) The scientists charged with assessing the herring stocks specifically (as opposed to diagnosing the whole ecosystem) have placed more faith in acoustic (sonar) surveys than they have in any evidence of herring found in the bottom trawl surveys. For herring, acoustic surveys “form the foundation for evaluation of the stock status” (Melvin et. al., 2003). A recent report from the outer Nova Scotian banks includes these observations: “Fleet activity/catch in the spring/early summer fishery on the offshore banks of the Scotian Shelf diminished in 2002. Acoustic recorders were activated on a few occasions but insufficient quantities of fish were observed to warrant analysis. Consequently, no acoustic biomass estimates were available from the Scotian Shelf in 2002. The fall herring survey (Oct 22 – Nov 2), which covered a large number of the outer banks, documented very little fish…The largest aggregation of herring was observed on the “Patch” and no herring were captured in any fishing set southeast of Halifax, excluding the Patch.” (Melvin et. al., 2003) There is reason, therefore, to suspect that herring might actually be declining on the offshore Scotian Shelf. Also, a “deterioration in the state of the herring stock” has been reported for the inshore component (DFO, 2004b). The hypothesis that the coastal ocean ecosystem is now heavily dominated by small pelagic fish seems to be contradicted by a lack of direct evidence of high herring abundance. Increasing bottom trawl counts of a common small baitfish, the sand lance (Ammodytes dubius), have been considered to be an important part of the evidence of the transition of the ecosystem to dominance by "pelagic fish," which have been speculated to be preventing the flow of food to the bottom. "Pelagic fish" tend to swim in schools and stay away from the very bottom water. The sand lance, however, is only a semi-pelagic fish. While it does swim in pelagic schools, the sand lance is more accurately described as "semidemersal" (Anon.). Besides releasing sinking eggs at maturity, the sand lance is often found in very close association with the sea bed. In fact, it commonly buries itself. Sand lance therefore seem most unlikely to have any capacity to prevent the normal flux of food to the bottom. Sand lance are regular food for larger bottom dwelling (demersal) fish. For instance, haddock, a fish which roots through the soft sea bottom for food, is a common consumer of sand lance. "Sand lance, as the name implies, are found on sandy bottom, both inshore and on the banks; they avoid rocky bottom. They occur in large schools and burrow in the sand at times to a depth of several inches; sometimes they remain buried in sand when the tide leaves the area...Over half of the food of haddock on the Sable Island Bank consists of sand lance." (Liem and Scott, 1966) Therefore, DFO's hypothesis that a great biomass of pelagic fish - largely herring, capelin, and sand lance - is currently causing the starvation of bottom fish by preventing the flux of food to bottom, seems to be contradicted by known aspects of the biology of these "pelagic" fish species. If the "small pelagic fish" are not causing the starvation of the bottom fish, then what is causing it? Is the ocean itself now "starving?" Might the upper region of the ocean water column also now be relatively “energy poor” compared to its previous condition, as is the lower region where the codfish live? The truth is that overwhelming evidence suggests exactly this, from declining zooplankton counts across the Eastern Scotian Shelf to a “coherent community-level reduction” in shoreline marine animal life. Barnacles, mussels, and other small animals and fish living near the shoreline have demonstrated a broad general decline in size and numbers, echoing and coinciding with the trends that scientists have described in groundfish. Seaweeds provide direct evidence of declining plant fertility at the ocean surface, of being “energy poor” today in comparison to seaweeds that grew here decades ago. The long-term decline in the availability of Irish moss on the Nova Scotia shoreline provides but one piece of such evidence. This broad scenario of declining life at the sea surface cannot be plausibly explained by pollution or by climate change, no more than the starving cod on the sea bottom can be. However, the larger changing picture, of the erosion of vitality of an ocean overall, can be explained by the cumulative effect of fishing, by the progressive removal of “biologically useful biomass.” Mr. Regan, five years ago, in 1999, I sent copies of my self-published book, "Wake Up and Feed the Fish! A new insight into the causes of the collapsing fisheries," to DFO Science and to the office of the Minister of Fisheries and Oceans. Then minister, Herb Dhaliwal, replied to me that this was of definite interest to him and that he would direct DFO Science to respond to me. I was told by scientists that my diagnosis of the cod problem - an inability of cod to find enough to eat - was simply wrong. I was naive, and I did not understand how the ocean works. Marine scientists at that time had alternate ways of interpreting the various data that I thought supported my conclusion. But it seems now that I was right. I had argued that cod are starving today because of centuries of fishing, because of cumulative bulk biomass removal from the ocean. Five years later, DFO has arrived at a remarkably similar conclusion. It is interesting that Choi et al. mentioned the problem of bulk biomass removal "without replacement," because this was also what I saw. I thought that perhaps we could help reverse the situation by "replacing" some of the missing biomass/food on the fishing banks, and that maybe we should try scattering edible human food wastes where fish or other sea creatures could eat them. I wanted to "feed the fish." This might help somewhat, but I now realize that it would be a delicate and risky venture, because the risk of depleting oxygen from the water by letting organic materials rot on bottom would be a serious hazard in many places. Carefully done, however, this strategy might help a bit. The most obvious intervention that we need to make, however, is to stop removing living biomass from the ocean. A catastrophe for the fishing industry, for sure, but the ramifications of causing greater starvation in the ocean are serious global ones; they affect even the stability of the atmosphere, the carbon cycle. Mr. Regan, I offer you a prediction today that over the next few years DFO scientists will discover new insights and will publish new papers describing the subtle specifics of the nature of the “biological usefulness” of “biomass” that swims in the ocean as fish. It will eventually be shown that an important part of the natural usefulness of fish is to enhance the fertility of the ocean ecosystem itself, and that this is why centuries of fishing caused the ultimate starvation of cod on the Scotian Shelf. Those big old bottom-dwelling cod did more that was "biologically useful" than to just eat a lot of herring: they also sent untold billions of their own excess eggs floating up to fertilize the surface water, and those fish thereby helped to ensure that more food would grow and sift down through the water column later, feeding everything. It will be further realized that all marine animals exert this same positive effect on ocean health and fertility, from small pelagic fish and groundfish, to seals and whales, and including all of the tiny forms of animal plankton. Unfortunately, however, this realization will signal the end of the prevailing “sustainable fisheries” scientific paradigm. But this establishment is teetering already…that much can be easily appreciated, and it is not too difficult to guess which way it will fall. There will soon be a major revolution in scientific thought about the ecological role and significance of all animals living in the ocean. Once DFO makes a more accurate assessment of the trends in small pelagic fish biomass, and it is crucial that they do this, the Eastern Scotian Shelf science team will be very close to seeing the big picture clearly. And they will see something that they were never taught to see before: that fishing has ultimately eroded the energy of the overall ocean ecosystem, because all fish, and all marine mammals and seabirds, naturally contribute to the health and enhance the fertility of the ocean itself. Humans have simply killed far too many of these creatures, by centuries of fishing, and we have thereby now dangerously lowered the energy of the ocean ecosystem itself. We have run up a huge debt. Important organic reserves in the sea, that we did not appreciate as such, have been significantly drained. It will eventually be realized that the ocean health enhancement provided by abundant large marine animal life extends even to helping ward off such modern ocean ills as “dead zones,” bacterial domination in coastal waters, and toxic algae blooms. The only real remedy for the problem of generally weakened ocean health will be for people to protect whatever is left alive in the sea and to allow marine animals to regain strength, and to rebuild ocean fertility, together: we will need to leave all marine life alone for some time. Impossible? Maybe, but this will soon be the objective scientific truth of the matter. I realize that admitting this to the Canadian public will be rough work for a Minister of Fisheries and Oceans. However, the sooner we bite this bullet, the better, because the health of the environment that our children inherit depends heavily upon our action – or our inaction - today. And a healthy ocean is crucial to all else; this is true beyond any doubt. As the Minister of Fisheries and Oceans, you need a well-informed, honest and impartial ocean science watchdog. As for myself, I find now, after years of being able to support my marine research independently, that I can no longer afford to continue to do so. Might I be able to help you? I will soon need to find a way to generate income. Any practical help or financial support would be greatly appreciated. Sincerely, Debbie MacKenzie Email: Codmother2@aol.com P.S. Following up on a couple of issues we discussed at our meeting in April: Thank you for ensuring that DFO scientists will finally give me at a hearing at the Bedford Institute of Oceanography. This has been arranged in a seminar format for September 15, 2004 - please let me know if you would like to attend this meeting or to send someone from your office. Also, did you or your assistant discover any signs of activity by MACO, the Minister’s Advisory Council on Oceans? How sad. Has the saga of the troubled northern cod now come full circle? Five hundred years ago it was claimed that one could harvest cod from Newfoundland waters simply by lowering a basket into the sea. In this latest pathetic twist of the story, it seems that harvesting the northern cod might again be that easy…because thousands of tons of them are floating dead on the surface of an inshore bay. The scientific opinion is that these cod have died from the cold. But that explanation at first sounds just a bit unlikely. Have not Newfoundland waters always been very cold? The cod population involved in this incident represents the last hold out of a once-phenomenal biomass that dominated the entire Grand Bank. And it now seems certain that cod will be unable to survive much longer in this precarious position. Why not? Frozen cod at Lower Lance Cove, Newfoundland, April 9/03.Photo courtesy Patricia Pike. Why did the cod die? The media report was based on an interview with a spokesperson from the Department of Fisheries and Oceans, as well as the observations of local residents. And the explanation is that the cod found themselves in water that had been “super chilled” and was therefore too cold for their survival. It was also noted that this phenomenon has been seen before in this area in recent years, but that on the other occasions only “small numbers” of fish had been affected. The important question posed today is “Why have such a large number of cod suddenly ‘frozen to death’ this year?” Stresses have been mounting on the northern cod that indicate that the marine environment has become increasingly hostile to its continued survival. But this does not mean simply that the ocean has become colder. A more plausible explanation is that the many shifting trends have been forced by an ever-dwindling food supply. Surviving northern cod are now increasingly concentrated in a few inshore bays (FRCC, DFO). This is in marked contrast to the earlier, long-established pattern where the bulk of the cod population migrated offshore to spend the winter in warmer, deeper water and moved inshore during the spring and summer months to feed. Cod that live inshore year-round enjoy a relatively greater availability of food, but they run the added risk of becoming weakened or killed by exposure to extremely cold (sub-zero) surface water. The water has not gotten colder, but it appears that a greater proportion of the cod are trying to survive in this precarious position. What is essentially a food shortage issue for cod could therefore be ultimately manifested as a ‘freezing to death’ issue. There are many other indications that food shortage is now a major problem facing northern cod. - Growth rates, and more significantly the condition (essentially the fat content), of cod has declined in recent years, and this decline has been sharpest in the areas with lower natural levels of food production (i.e. offshore Newfoundland waters as compared to inshore, and in Nova Scotia a marked drop in condition has occurred on the Eastern Scotian Shelf as compared to the richer Bay of Fundy). - Age-at-maturity in northern cod has declined significantly (DFO, 2003). The tendency of fish to become mature at smaller sizes and younger ages is known to be a possible consequence of a declining food availability (Stearns and Crandall, 1984). - In recent years, scientists and fishermen in Newfoundland (and elsewhere in Atlantic Canada) have repeatedly expressed concern at the decline in capelin, traditionally the major, oil-rich prey of the northern cod. Scientific surveys on the Grand Bank suggest that a large decline in capelin abundance has occurred there. Capelin are also smaller now, on average, than they were in the past. - Scientific monitoring has revealed a decades-long trend of a declining abundance of zooplankton* in Atlantic Canada. And zooplankton (tiny animal-plankton) are the major food of young cod, as well as the food for capelin. (* This development has received far less scientific attention than it deserves, which represents a major weakness in DFO’s Science program.) - Accelerated natural mortality due to poor physical condition (post-spawning mortality) was believed to have been a factor in the sudden crash of the cod stock that occurred in the early 1990s, and which coincided with a short term dip in water temperature. - The age of cod being consumed by harp seals has been inexplicably rising. From DFO (2003): “From 1986 to 1996 cod age 0 and 1 were the predominant age groups found in harp seal stomachs. In 1997 and 1998 older fish (ages 3-5) were the dominant age groups and fish as old as age 7 were found more frequently than in previous years.” Since harp seals are not growing bigger or stronger, this pattern suggests that their cod-prey are becoming physically weaker and increasingly unable to escape predation. In the earlier years, it seems most likely that the seals refrained from eating the larger cod simply because they could not catch them. The role of natural predators is to enhance the health of its prey species by selectively removing the weakest individuals. Adult cod slowed (or killed) by factors such as food starvation, extreme cold, or oxygen deprivation, would become easy prey for seals that they could have avoided had the fish been in better health. Why are the cod concentrated in Smith Sound? A relatively dense aggregation of Atlantic cod has persisted in Smith Sound, in an inner region of Trinity Bay, following the demise of the bulk of the larger offshore stock component. Why have cod persisted in this particular location? Faced with an environment that is producing ever-lower quantities of their food, a fish such as the Atlantic cod will make any and all possible adjustments that will enhance its survival odds. Besides slowing the individual growth rate, reducing body fat stores and reproducing at smaller sizes, the fish can be expected to contract its geographic range to the area that naturally produces the most edible material. Due to the nutrient input from terrestrial run-off, inshore locations such as Smith Sound produce somewhat more food, and will ultimately become the only remaining viable habitat for cod. But, as general food availability declines, susceptibility to death by ‘freezing’ in these relatively shallow, inshore areas can be expected to increase. This is because poorly nourished animals have lowered resistance to all physical stressors. What explains the timing of this particular fish-kill? If the immediate cause of the recently reported cod deaths was cold water, why did this occur in early April, and not in January or February? It seems unlikely that much heat remained in the surface water of Smith Sound during those winter months. This is supposedly explained by some vague “atmospheric effect,” but the factors previously discussed may be more important. First of all, fish with borderline energy reserves to withstand the intense cold would be expected to run out of energy and perish at the end of winter. However, the suddenness of this event and the fact that cod of many different sizes died simultaneously, suggests that some other environmental variable may have abruptly changed for the worse and contributed directly to their deaths. The following is speculation on my part, but it will be interesting to see what the final verdict of science is on the cause of this fish kill. A lack of oxygen in the bottom water of Smith Sound may have contributed to fatally ‘drawing’ the cod to the surface. It is now early spring. This is the time of year when daylight lengthens, seawater becomes less turbulent, and the ‘spring bloom’ of phytoplankton occurs in the North Atlantic Ocean. In this area, these blooms have been noted to be becoming more intense, although somewhat shorter lived, in recent years as compared to decades ago (Gregg and Conkright, 2002, DFO, 2000). The increased intensity of the ‘greeness’ relates to the fact that tiny algae are more numerous in the surface water. Since zooplankton normally eat the phytoplankton, a decline in the numbers of zooplankton can readily be seen to be related to the observed increase in ‘greeness.’ One problem, however, is that uneaten algae will sink to the bottom and undergo bacterial decomposition, which can reduce the oxygen content of the water to levels below that needed for fish survival. This scenario may have developed in Smith Sound, and in such a semi-enclosed inshore area the whole effect may easily have been exacerbated by nutrient input from terrestrial sources, such as spring run-off. (The loss of oxygen from the bottom water in Smith Sound may have been severe enough to kill bottom life there, such as crabs, and if this is discovered to have occurred it adds considerable credibility to this hypothesis.) The loss of zooplankton can therefore be seen to contribute in multiple ways to disabling the ability of the ocean to sustain fish such as cod. Fishermen cannot be blamed for failing to see the zooplankton decline, but for DFO Science this seems to be inexcusable. Graphs above copied from DFO SSR G3-03(2000), page 6. Click to enlarge. I have added the red and green lines, just my 'eyeball' linear regressions, to show the rising tendency of the three plant (phytoplankton) indicators and the declining tendency of the three animal (zooplankton) indicators. This interpretation agrees with DFO's text comments at top left of the page. My final observation is that the direct effect of seals on zooplankton is a positive one. Seals excrete copious amounts of live invertebrate (worm) eggs directly into the water. These little creatures ‘are’ zooplankton, and they are also eaten by larger forms of zooplankton. The entire assemblage of tiny planktonic animals is critical to zooplankton health and to the control and moderation of phytoplankton growth. Therefore, these, and the seals, are the last creatures that should be ‘excluded’ from Smith Sound. Even in a hypoxic bay, seals can survive, eat the dying fish and convert at least a portion of that food into live zooplankton, while avoiding some degree of the bacterial decomposition which would necessarily occur should many dead fish sink to the bottom. Thus an air breathing, zooplankton excreting predator, such as the seal, is in a unique position to help correct this type of unhealthy scenario. The human “stewards” must quickly realize these things, and learn to value the seals as agents that actively promote the health and stability of marine ecosystems. The FRCC has recommended that “a designated Seal Exclusion Zone Control Team should be established immediately to keep seals out of Smith Sound year round.” (FRCC, 2003). This plan is sheer folly, and will undoubtedly hasten the imminent total disappearance of the northern cod. The “stewards” should now give careful consideration to a truly original approach; they should consider trying to have an active, positive impact on the health of cod; I think they should try feeding the fish. - Debbie MacKenzie The week of April 7-11, as a steady stream of frozen cod has continued to “bubble to the surface” of Smith Sound, so has the frustration, anxiety and anger of the local people. “It’s imperative that they get the answers and none of us are going to be settled and be satisfied until we get the answers.” -- John Efford, MP “It’s a crime for this to happen here…Seals caused it, that’s all that’s wrong. That’s the bottom line…if they don’t do something about the seals there won’t be a cod left in here.” -- Gilbert Penney, fisherman The first theory favored by fishermen, and considered by scientists, was that the incident had been triggered by seals chasing the cod from a region of safer, warmer bottom water into the too-cold surface water where they came into contact with ice crystals and froze to death. However, by Wednesday afternoon, the government fisheries research vessel Teleost was on the scene and scientists had determined that the entire body of water in Smith Sound was very cold throughout the water column. Water temperatures were discovered to be as cold as -1.7 degrees Celsius. According to DFO’s Dr. George Lilly, “That’s about as cold as sea water in our area can get; it can get a tiny bit colder than that, but not much more…the water is cold everywhere -- there’s no such thing as warm water in which the fish might have been living, and then they ended up being chased by seals, or fled from seals into the cold water.” So, the main working hypothesis at this point seems to be that the cod have been killed by harsh environmental conditions, specifically unusually cold water, which has likely resulted from what has been a colder winter in this area than we have had for a couple of decades. While their survival at these very cold temperatures may be precarious, and can end suddenly if cod contact ice crystals (they can freeze fast, almost in a snap) they do produce a type of internal antifreeze and can exist in a “super chilled” condition to some extent in sub-zero water temperatures. And many cod are still managing to survive in the very cold water. April 11, DFO scientist John Brattey described the latest on the cod deaths in an interview reported by CBC: “Brattey says the water remains the coldest that the department has ever recorded in the area, and some fish will continue to die. He says tests show some of the cod have an anti-freeze protein, while others don't. Otherwise, the dead cod appears to have been healthy up until it was instantly frozen by contact with ice crystals. Brattey says the organs of the dead cod are frozen solid, even though the flesh of the fish is pliable.” (CBC St. John’s news website) The avoidance of contact with ice crystals could clearly best be maintained by fish staying in the deeper waters layers, and this has been the usual winter habit of Smith Sound cod according to previous scientific observations. And Brattey has also reported that acoustic surveys this week have revealed "one very large, dense aggregation of fish moving around in the sound," and that sampling these fish has shown them to be in good health. So…we had a hard winter, and the water in Newfoundland is unusually cold, and the freezing death of what may amount to thousands of tons of cod at this time has simply been caused by a ‘freak of nature,’ an unpredictable and unavoidable turn of events? Maybe…but it seems unlikely that the “cold water” explanation will satisfy the local people. People have lived in this area for a long time and many can remember colder winters, but no-one remembers seeing such a fish kill here before. People involved in the cod fishery have been interviewed on radio and quoted in the print media: “I’ve been fishing ever since 1959 until ‘92 when she closed -- never seen fish like it before.” - fisherman “We want to know the reason, science is there to give us a reason…We want to know the truth of it. It’s heartbreaking…there’s got to be answers. There’s a reason for everything.” - fish plant worker “Explanations by…officials, of cold water columns don’t cut it. Codfish have been avoiding cold water columns for hundreds of years.” - Earle McCurdy, FFAW ------- But…“why here, why now is not clear.” - DFO, April 11 The cold water is undoubtedly significant, but a puzzling feature of this incident is the suddenness with which it occurred. And why now? Something seems to have changed abruptly which tipped the balance and caused Smith Sound to become hostile to the cod. And it is crucial to determine exactly which variable that was. For how long has the entire water column at Smith Sound been super-cold? Ongoing monitoring of water temperatures has not been done, so it is not possible to answer this question with any certainty. However, barring some very unusual weather pattern, it might be reasonable to assume that there has not been a recent abrupt temperature drop. Water temperatures may have been as low as the most recent measurements for months. Why is the cold water killing fish now? An illustration of the abruptness and the timing of the increase in chlorophyll that occurs during the spring bloom in Atlantic Canada can be seen in the solid lines in this figure, taken from DFO SSR G3-02(2000) (click to enlarge image). There is, however, one oceanographic variable that probably has recently changed quite abruptly in Smith Sound, and that is the concentration of chlorophyll in the water. This is known to rise sharply, as marine algae numbers increase “explosively” in the "spring bloom" at this time of year in this part of the world. ...