The reappearance this season of bigger than normal salmon in the beat, throws up quite a few possibilities. As usual, where fishing is concerned, there are a lot more questions than answers. It is very difficult to work out what run behaviour any given salmon run is using, the only sure fire way is by scale reading and to get a workable base this usually involves sampling fairly large numbers, as runs often overlap each other and as can be seen when you bring into the equation hereditability that is mentioned later.
Statistics depend heavily on what year the survey was taken. Over the last five seasons I have noticed an increase in very small grilse appearing in the Amat beat earlier in the season, they were in evidence this season again over the first few days of May. There is without doubt more big fish this year in the Amat beat, as their was two years ago in 2001. This of course could be just a freak occurrence as with the grilse, but it would be nice to think that big multi sea winter salmon are surviving and returning to spawn in alternate years, repeat spawners fall in to three categories. Salmon that spawn alternately, salmon that spawn consecutively, and salmon that combine both these patterns, surveys done in North America showed that a high percentage of repeat spawners spawned first as grilse and that after their second spawning they will stay in the same pattern, entering the river at same time each year with a higher percentage of them being alternate spawners. The biggest percentage of any run are returning for the first time either as 1SW, or 2SW fish they will be carrying approx 650 to 800 eggs per 1lb body weight but the repeat spawner could be carrying up to 45 percent more eggs! and their genetics will be invaluable to the river or an area within the river. Of 8000 eggs deposited only approx 2 spawning adults will return to the river from this batch. Global warming? if there is such a thing is causing a lot of discussions if not arguments. Certainly over the last 10 years there can be no doubt that we have had freakish weather with amazing temperature readings at both ends of the scale in fact the nineteen ninety’s was the warmest decade of the twentieth century. Temperature of course governs practically all salmons behaviour, about seven years ago in the winter we had a temperature here at Amat of minus 26 degrees but its usually been at the other end of the scale that there has been unusual readings, in Feb 98 we had a water temperature of 51 degrees, this happens fairly regularly over the last ten years we have had February temperatures of around 42 degrees and we have certainly had these temperatures in early march, these on average would be 5 or 6 weeks earlier than you would expect. We had the water temperature at 42 degrees, in February this year and on April 15th this year we had a water temperature of 56 degrees, salmon were attempting the big falls at Glencalvie and by the end of that week they were going over, which is the earliest I have ever seen, of course we had the heat wave in August with a water temperature of 71 degrees! The major effect of this the warming up of the oceans, El Nino etc, the average temperature of the waters around Great Britain in the North sea and the Irish sea has warmed up 2 degrees in the last 20 years this is undoubtedly affecting the salmons sea life, affecting their food sources, timing of migrations, and all the complexities that go with that. The surface temperatures of the sea ideally should be 8 to 10 degrees, for migrating smolts the shock of higher temperatures can cause stress related mortalities. No matter how hard we try to understand their time spent at sea ultimately at present we will have little or no effect on this period, but the most important temperatures for us are the early ones in the river these temperatures are what determines when the eggs will hatch Smoltification ect, and for fishing purposes when we will get our first salmon run into Amat. Studies done into salmon genetics has came up with a formulae known as hereditability factor which evaluates the degree to which genetics, (which are fixed), and environment, (which changes), influence grilsification. In one study the hereditability factor was .22 for genetics, meaning that environment played a very significant part 80% in determining whether fish became grilse or multi sea winter salmon. Basically this means that depending on the prevailing environmental conditions there may be 80% more or fewer grilse in any generation at any given time. In the scale sampling study carried out on the Carron a few years ago, of the only fish identified as having spawned previously all had done so as grilse. During the same sampling the scales of a 10.5 lb fish showed it to be a grilse, and a 4.25 lb fish was in fact a salmon. A few years ago it was a popular belief that to many grilse would lead to the grilsification of your river as seen from the hereditability studies, nature and environment has a wonderfull way of ensuring its own survival. It has been proved that pure spring cocks and pure spring hens produced over 65% grilse, then we must also assume that being multi genic a proportion of the progeny of large M S W hens that are fertilised by grilse or even precocious parr, will be M S W fish. So these grilse are very valuable to the spawning population in the system. At Amat in the last seven seasons we have released 995 salmon and grilse releasing a mixed bag, to coin a phrase, as we have done would appear to be less regimented, less intrusive, we can work with nature, very seldom do we equal it let alone better it. A quote from a paper on this subject states, “ Salmon populations are highly structured geographically and genetically among and within rivers caution must be exercised regarding catch figures from different rivers or different parts of rivers ineffective interventions will store up even greater problems for future.“ We know that smolts will return to the actual pool they were released or were born in, so it would be nice to think that these big salmon are returning to the Amat beat. Two seasons ago in September a 27lb salmon was caught and two others of around 20lbs were lost. I did see two very large fish at spawning time one estimated at around 25lbs, the other around 30lbs. Around 4.5% which is not a lot is thought to survive to return and spawn again, so you are talking of very big fish returning if they survive. This season two big fish were lost, other than the three big ones that were landed, it would be fair to assume their may have been the odd other one. I did in fact see a big salmon show in the tail of the Rock pool on Oct 18th but this of course could be one of the released ones. Ironically this season I caught and released the biggest salmon I have ever had at 33lbs and the smallest I have ever caught. I was out with Alan Hancock in June when I landed a 2lb grilse in the Corner pool, in fact it may not have gone 2lbs had it been weighed, hopefully both will survive their very complex lifestyles and return again. Very interesting work is being done on the Miramichi river to determine why salmon presmolts begin moving downstream in the autumn of the year before they leave the river, two current theories are.( 1 )This is an adaptive movement that places fish closer to the sea so they can move out during the narrow window of optimal conditions in late spring. Or ( 2 )They have out grown their habitat and they need suitable food sources to overwinter this again would fit in with environmental change and is the one I would favour. The limited initial results are very interesting and show that the presmolts are only moving relatively short distances before stopping to over winter. It therefore looks as though they simply out grow their home stream habitat. The initial results show that some precocious parr after surviving spawning are also descending. So although damage is undoubtedly being done at sea, at present all we can hope to do is something at home.