At times it can be very difficult for the outsider to make sense of the figures that relate to the activities of those trying to remove salmon from the water, either by rod or net.
Earlier this week the Scottish Government published the provisional fishery statistics for the 2013 season.
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The total reported for salmon caught by rods, including those released back into the water, was 66,387.
This apparently was the lowest reported catch since 2003 and was 74% of the previous five year average.
Also "the proportion of the rod catch accounted for by catch and release is the highest reported since these figures were first recorded in 1994. In 2013, 92% of rod caught spring salmon was released, as was 80% of the annual rod catch."
According to anglers this was because the 2013 summer drought caused very low flows in most rivers so salmon were simply unable to access their rivers of origin, forcing them to run the gauntlet of coastal nets for weeks on end. Anglers don't have much time for Scotland's netsmen, nor indeed fish farmers.
So the controversial section was on netting which was said by the Scottish Government to remain at "historically low levels". While the figures for "effort", the number employed and time spent, were amongst the lowest recorded.
"Fixed engine netting" apparently is the archaic term to describe the nets used since the early 1800s to catch salmon outside estuaries. The total for this sector was 16,732 salmon.
Meanwhile the "net and coble" approach, which dates back at least to the 12th Century, is the only method of net fishing permitted within estuaries. It accounted for 7,579 salmon last year.
But on hearing of these "historically low levels" of netting the Salmon & Trout Association (Scotland) issued a statement: "Netting catch of salmon in Scotland leaps by massive 50% in 2013. Scottish Government is presiding over 'unrestricted wholesale slaughter'."
Were the anglers reading the same figures? Yes and the S&TAS was right. The number of salmon killed in nets in 2013 was indeed 50% higher or there about than in 2012 .
The point was underlined:
"The 2013 net catch of 24,311 salmon compares with 16,230 in 2012 and 19,818 in 2011. In contrast the rod catch dropped to 66,387 in 2013 (the lowest figure since 2003) from 86,013 in 2012. 80% of the 2013 rod catch were released by anglers back into the water."
Indeed Andrew Graham-Stewart, S&TAS Director went further: "The figures for 2013 exposes the absurdity of recent statements by Scottish Ministers that salmon netting in Scotland is declining. In the last three years dormant netting stations have re-opened and netting effort has increased substantially. The quantum leap in the netting catch in 2013 shows once again that salmon conservation is simply absent from Scottish Government's agenda. On the contrary it is permitting much greater levels of indiscriminate killing by nets of an iconic species that is already under considerable pressure".
As to the netting catches being historically low, he said: "It is disingenuous of Scottish Government to compare current netting catches with those of earlier decades - when marine survival was some five times greater and consequently salmon were abundant. The situation today is entirely different and at the very least Government should impose strict catch quotas on the netting companies."
But figures can be as slippery as salmon. Over the past decade and a half they don't quite support the idea there has been a remorseless increase in catches by netsmen.
The combined netting total in 2013 may have been 50% higher than 2012, but it was smaller than 2010, 2006, 2003, 2001 and 2000. Indeed the figure for that last year was 46% higher than 2013.
But the anglers aren't exaggerating when about the dramatic drop in salmon making it back to the rivers from sea.
In 1967 a total of 604,960 were caught by rod or net .The comparable figure for 2013 was just 90,698.
However the official Scottish Government position provides for greater optimism:
"The recent assessment of the status of Scottish Salmon Stocks by Marine Scotland Science suggests that the overall number of salmon returning to Scottish rivers has increased over recent years. The Report recognises that there is a variation in trends of abundance among components of the stock associated with particular regions and run times. Overall numbers of spring-running salmon have generally stabilised over recent decades and both summer and autumn stock component demonstrate an increasing trend. "
So it seems to be case of deciding whether your salmon river is half full, or half empty.