Freshwater animals over 16 years old

Freshwater animals over 16 years old

Priorities for the DREVO Nature Passport

Here we need to clarify the criterion:There are relatively few species whose average lifespan in the wild has been proven to exceed 16 yearsFor most fish, there is no reliable average age known, butmaximum recorded age. Therefore, not all species that can sometimes live up to 16 years should be certified, butspecific confirmed old individuals.

The most suitable groups are sturgeons, large catfish, eels, long-lived carp, freshwater turtles and bivalves.

1. Top priority fish

Sturgeons are particularly important: some species live for decades, mature late, and don't reproduce every year. For example, the pallid sturgeon can live for at least 80 years, and the lake sturgeon, potentially for around 150 years; females of some sturgeons first mature at around 15–20 years. Therefore, a 16-year-old individual may only be part of the reproductively most valuable part of the population.

2. Which fish should not be automatically certified after the age of 16?

For such types it is better to use statusmature individual, and issue a passport only after confirmation of age.

3. Freshwater reptiles

For turtles, 16 years is a good threshold for individual certification: this is already a mature individual, capable of participating in reproduction for many years.

Priority:Native and rare turtles. The invasive red-eared slider may be long-lived, but it should not be given conservation status based solely on its age.

4. Freshwater mollusks

This is one of the most important groups for the program.

Freshwater mollusks are especially valuable aschronicle of the state of the riverAge can be estimated by the growth layers of the shell, and the tissues and valves accumulate evidence of prolonged exposure to pollution. Pearl mussels can reach 100–200 years; some other river mollusks live from 20 to 100 years.

It makes sense to create a separate status for mollusks:

DREVO Living Water Archive – a living archive of water quality.

5. Crayfish and other invertebrates

Crayfish age is more difficult to confirm due to molting. Therefore, it's better to certify the River Rover Scout not by its estimated age, but by a combination of:

the size;

half;

repeated observations;

tags;

tissue analysis or other validated methods.

6. Semi-aquatic mammals

Here the 16-year threshold is less universal.

For beavers, it is more useful to have a passport not only for an individual animal, but also forfamily, a dam and the wetland complex it created.

7. Recommended levels of certification

Level A - Mandatory Individual Passport

all sturgeons over 16 years old;

European eels over 16 years of age;

large catfish over 16 years old;

local freshwater turtles over 16 years old;

pearl mussels and rare bivalves;

particularly rare individuals, regardless of age.

Level B - passport after age verification

carp and carp;

pike;

slush;

bream;

tench;

zander;

large crayfish;

beaver;

otter.

Level C - Population Passport

small fish;

amphibians;

most crayfish;

snails;

colonial invertebrates;

species that cannot be reliably distinguished individually.

8. What the River Rover Scout can detect

River Rover Scout should not automatically declare a fish to be 16 years old based on size alone.A large, fast-growing specimen may be younger, while a small, slow-growing specimen may be older.

Age is confirmed through:

scales;

otoliths - usually only with scientific selection and not always without death;

fin rays;

bone structures;

PIT marks;

genetic identification;

history of repeated observations;

registered date of issue.

9. Optimal DREVO model

I recommend replacing the single rule:

"All animals over 16 years of age receive a passport."

to a more accurate model:

"All confirmed individuals of long-lived species who reach 16 years of age are entitled to an individual digital passport; rare and especially valuable species receive a passport regardless of age."

Top priority for Europe

beluga and other sturgeons;

sterlet;

European catfish;

European eel;

large carp;

pike;

slush;

European pond turtle;

pearl oyster;

rare pearl barley;

broad-clawed crayfish;

beaver - individually or in a family group.

The most valuable objects of age certification will be sturgeon and freshwater mollusks:They are capable of storing in their biology the history of a river spanning several human generations.

DREVO Fish Passport