Friday, 23 October 2020

Migrants by sea and air




Saturday (24/October) is World Fish Migration Day, launched this year as a one day global celebration to create awareness of the importance of free-flowing rivers and migratory fish.


I must admit I would have been hard pushed to name more than three species that migrate around European waters – Atlantic salmon, European eel and sea trout – but the map highlights at least four more who are living lives of varying success.



The Allis shad is a mackerel-like fish that lives most of its life at sea, returning to its natal river to spawn beneath rapids, the only known spawning river in the UK being the Tamar in the West country. It is doing better elsewhere, mostly in French waters. A bit grayling-like in appearance the status of the houting, a member of the salmon family, is contentious. There has been €20 million project to restore the Danish houting but there is some argument whether this is a ‘true’ houting; if it isn’t the species is classified as extinct. On the other hand, the Vimba bream that migrates from the Baltic into the rivers of Eastern Europe and Russia is doing well.


The largest of our migrants is the Atlantic sturgeon that may grow as long as 20 feet, reach 800 pounds in weight and doesn’t reach sexual maturity until around 15 years of age, living as long as 60 years. Until a few centuries ago Acipenser sturio was commonly found in British rivers such as the Severn, Avon, Ouse, some Scottish rivers and the Thames, so much so that under UK law the sturgeon, along with whales, are classified as ‘Royal fish’ and therefore property of the Queen. However, since the last one was caught in 2013 (probably a discarded pet) don’t expect sturgeon on the menu anytime soon when you dine at Buckingham Palace.


Unlike many fish, sturgeon was not exploited until relatively recently; for the most part it was considered worthless, at best avoided, as its rough skin shredded fishing nets. However, once its value for caviar was recognised, along with its leathery skin used in clothing and bookbinding, and the blubber processed into isinglass, a gelatinous substance used in clarifying jellies, glues, wines and beer, its days were to be numbered.


Today there are estimated to be at most 750 mature adults living, with the sole spawning site being the Garonne River in France, where it last spawned in 1994 so it is, unsurprisingly, on the Critically Endangered list.


If you would like to know more, watch the Love Flows film or participate in World Fish Migration Day with 300+ online events click here ....



A Russian 40 Kopek stamp from 1959 featuring the Atlantic sturgeon



Alaska to New Zealand non-stop


Did you read about 4BBRW? The name does not give you much clue as to what or who 4BBRW is, but it is in fact a godwit, a bird that splits its life between the sub-polar extremes of our two hemispheres, migrating between its summer haunt of Alaska and New Zealand.


Last month this particular Bar-tailed godwit, which weighs no more than a pound (it eats to double its normal weight in preparation of the journey) set the record for the longest non-stop migration on record, flying the 7,456 miles in 11 days. How did our godwit do it? After all, the journey is almost entirely over the Pacific Ocean for a bird with no capacity to feed, rest in water or sleep on the wing.


Well, despite what you might think, it doesn’t take the most direct route. The godwit clearly has some sort of avian algorithm that allows it to navigate the route by hitching a ride on the most favourable winds whilst anticipating approaching high and low weather fronts.



It is surprising how many birds migrate; it is estimated worldwide about 4,000 do so, which is 40% of all species, in the search of better feeding and breeding grounds. However, in the UK we are way below that percentage which, I guess, speaks to our relatively benign climate with only around 70 migrants amongst the 574 that live here for all or part of the year. I’ve struggled to find any British bird that matches the godwit for travelling but the Willow Warbler makes a fine effort for such a small bird arriving as it does from Southern Africa in late spring having flown 5,000 miles over mountains, deserts and seas.


How do the Willow Warblers and their like find their way on a route that they are often charting both alone and for the first time? Scientists think that birds use their sense of smell to follow odours, their remarkable eyesight to follow the Sun, the stars, the Earth's magnetic field, and landmarks, and wind directions to achieve navigation. And a bit like the European eel, just to mix things up, the return trip can often follow an entirely different route.


And why do they travel at all? Well, obviously avoiding the extremes of climate is a motivator but the length of the day, scarcity of nesting sites, easy availability of food and predators have all aggregated over time so birds seek the best way of preserving their particular tribe, even if it involves massive relocation with all the risks that that entails. But then again migration is not always a baked in evolutionary strategy. Sometimes it is driven by necessity, irruptions as they are called, when birds flee their native land when a primary source of food fails. For the recipient land these are more invasions than migrations, such as when Waxwings appear along the east coast of the British Isles, in the wake of the occasional failure of the Scandinavian rowan berry crop.




Where is the Piddle valley?


I was delighted to see that Nether Wallop made it on to the UK map of the weirdest, silliest, oddest and rudest place names that was doing the rounds on social media last week.


Rivers usually provide a thick seam for cartographical mischief makers so I was surprised that Dorset’s Piddle valley didn’t make the cut. As any schoolboy will attend, it is a glaring omission.





Video of the week


I know you all like a bit of fishing action and the trailer for the International Fly Fishing Film Festival is a great opener for the weekend.


It has been around for a while but as far as I know, thanks to Covid, the live 2020 screening never made it to our shores. So, enjoy the trailer (love that polar bear) and if you look down the righthand side of Vimeo there are a dozen more trailers which are great fun in themselves.


If you are keen to watch the whole show it is being released for 48 hours on December 3rd. A single pass is $15 or $30 for a group. Get in the beers and make it a party! More details here …..





This week as we return to the random collection of questions to confound, dismay or delight.


The answers are, as ever at the bottom of the page.


1)     Which breed of sturgeon produces the most valuable caviar?


2)     What is the most expensive stamp ever sold?


3)     Today is Mole Day. What does it celebrate?



Have a great weekend.



Best wishes,



Simon Cooper

Founder & Managing Director




Quiz answers:


1)     Beluga. Others are Sterlet, Kaluga hybrid, American osetra, Ossetra, Siberian sturgeon and Sevruga.

2)     A British Guiana One-Cent Magenta sold at auction in 2018 for $9.48m

3)     Mole Day is an unofficial holiday celebrated among chemists, chemistry students and chemistry enthusiasts on October 23, between 6:02 a.m. and 6:02 p.m, making the date 6:02 10/23 in the American style of writing dates. The time and date are derived from the Avogadro number, which is approximately 6.02×1023, defining the number of particles (atoms or molecules) in one mole (mol) of substance, one of the seven base SI units. [Yes, I’m none the wiser either].


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