Fishery managers are job for an finish to dredging in Aberdeen gulf when immature salmon are migrating to a sea.
They contend a entertain of all tagged smolts were mislaid in a gulf final year when dredge boats were active.
Salmon numbers in many rivers have been experiencing long-term decrease and millions is being spent perplexing to settle a reasons.
Aberdeen Harbour Board has insisted a couple between mankind and dredging is “improbable and speculative.”
Scientists have been tracking immature salmon and fish on a River Dee given 2016 by inserting radio inclination into a fish while they are upstream.
Listening inclination are afterwards placed during unchanging intervals along a stream to settle a length of time it takes to strech a sea.
River executive Dr Lorraine Hawkins said: “In a final 5 years we’ve seen reduce catches on a River Dee and many other Scottish rivers.
“We’ve found utterly a high detriment rate in a river, in a sequence of 20% to 40%. Last year, for a initial time, we saw additional mankind of smolts in a harbour, in a sequence of about 27%.
“It did so occur that there was upkeep work going on in a gulf during that time. It does not meant that was a means of a waste though we would unequivocally like to work with a gulf house to demeanour some-more into this.
“Smolts are so exposed and we only have to yield a pinnacle insurance to make certain they get to sea safely.”
Aberdeen gulf is an critical pier for a oil and gas attention with about 6,800 vessels regulating it annually.
It was built where a River Dee meets a North Sea.
A orator for Aberdeen Harbour Board said: “One of a principal responsibilities for any gulf management is to say a abyss of a water, by dredging operations, and to safeguard a protected thoroughfare of vessels.
“This has been an activity that has been carried out, comparatively unchanged, in Aberdeen Harbour for hundreds of years and is an activity protected by Marine Scotland.
“Historically, no investigate has suggested any couple between gulf operations and salmon numbers, and a formula from a initial dual years of this investigate – of that we are a funder and an active member – have shown 0 smolt mankind within a gulf territory of a River Dee.
“For it to be surmised that North Harbour operations have unexpected turn a contributing cause to a detriment of smolts is both extraordinary and quite speculative.”
The start of Feb outlines a commencement of a salmon fishing deteriorate on a River Dee.
It is estimated that angling generates about £15m for a internal economy and supports hundreds of jobs.
Last year calls were made for a “sensible debate” on either some birds should be culled to strengthen fish stocks.
The goosander duck, in particular, are feared by anglers since of their adore of salmon.