The life of a kob, Namibia’s most popular line caught fish!

I’ve received this from a friend of mine. I decided to share it for information sharing purposes. Not sure who the author is but I agree with his sentiment.

The life of a kob, Namibia’s most popular line caught fish, is a mystery to most people but very

interesting to those in the know. It’s a life fraught with danger from natural enemies throughout its

different lifecycles up to a maximum age of about 28 years. And then of course there is man

waiting with his baited hooks and nets. Silver kob (Argyrosomus inodorus) occurs along Namibia’s

1600 km long shoreline roughly from Meob Bay in the Namib Naukluft Park in the south, across

the centrally located West Coast Recreational Area to about halfway to the Kunene River in the

Skeleton CoastPark.

 

These facts and what follows are results obtained through the Namibian Angling Fish Tagging

Program (NAFTAP) that was initiated 20 years ago. To date almost 30 000 kob were tagged of

which 456 were recaptured giving us their size/weight ranges, growth rates, geographical

distribution and migratory cycle. Biological studies showed us what they eat, how they reproduce

and how they age. Most fish were tagged in the areas closed to shore anglers, principally to

determine to what extent those tagged fish would move into or “seed” the “open” area, the West

Coast Recreational Area which constitutes only one fifth of the coastline.

It is in this stretch of coast that about 180 000 angler outings occurs annually. And yes with

today’s modern rods & reels, GPS points and 4×4 vehicles sucha number of anglers can overfish

the kob stock if strict angling regulations are not in place. By interviewing anglers while they are

actively fishing and sampling their catch (roving kreel surveys) we can, by using a specially

designed computer model, determine how many kob are available to harvest and based on that

adapt the daily bag limit per angler in order to sustainably utilise the kob stock. Thus, in 2001 the

bag limit was lowered from 30 fish per angler to only ten.

To follow the life of a kob we have to start in the Skeleton Coast Park where the main breeding

stock lives. Here the cold Benguela Current provides a rich diet of small pelagic fish, chokka and

shrimps for them. These adult fish are between 60 to 120 cm in length in an age range of

between 5 and 28 years old. Large adults, called spawners, of 70 cm and bigger start their

annual spawning (breeding) migration southwards against the surface currents, at the beginning

of the austral summer to their main spawning grounds, Sandwich Harbour and Meob Bay, at the

southern end of their distributional range. This is also the time when the warm Angolan Front

starts pushing southwards bringing warm, saline water and sometimes tropical fish species such

as shad and garrick from mid-Angola as far south as Swakopmund.

On their way down the coast some large predators such as pelagic sharks will catch a few of

them while shore anglers at Terrace Bay and Torra Bay will catch many of them. They will also

pass though the seal colonies of Möwe Bay, Torra Bay, Toscanini and Cape Cross but seals are

more interested in the oily and tastier small pelagic shoaling fish such as pilchard or horse

mackerel which they can catch easily rather than spending a lot of energy chasing a fast

predatory fish such as kob. After feeding at Toscanini Bay they will cross into the WCRA and will

appear briefly at popular angling spots such as Horingbaai, Mile 72, Jakkalsputz and so forth

where they will feed in the shallow bays. Surprise, here hundreds of baited hooks from shore

anglers awaits them but it’s only those anglers that can cast far that will be lucky and many

spawners will end up in the bag.

In addition, between Henties Bay and Swakopmund skiboats will now hunt them just behind the

breakers and their numbers will decline further as many are hauled aboard. This is very easy

once the onboard fishfinder has located the school. Just drop the baited hook overboard and it

will instantly be swallowed by the hungry fish. Now comes the last gauntlet before the safety of

Sandwich Harbour namely the famous Paaltjies numbers 1 to 3.

The bush telegraph worked well and here hundreds of shore anglers will await their arrival, even

anglers from South Africa will arrive on short notice to take part in the feast. Fortunately the kob

keeps moving and soon the lucky ones will reach the safety of Sandwich Harbour which is closed

to angling from 25 January to 15 April each year since 1992 specifically to offer protection for

these spawners. Since 2001 when the angling permit system has been introduced, a maximum

size limit has also been introduced through which an angler may only keep two kob of 70 cm and

bigger in a further effort to protect the breeding stock.

Spawning now takes place between here and Meob Bay, 180 km further south. The females will

release their eggs in batches while the males fertilises them with their milt. Some will be caught

by the research team here for research purposes and they will be measured, weighed, tagged

and released again. This procedure takes about 1-2 minutes. By the end of March when the

water temperature decreases to about 15°C they will begin their long journey back home moving

slightly off-shore.On their way they may be caught by mid-water trawlers or purseseiners but the

high bycatch levy on kob makes the skippers think twice before hauling anyaboard. During the

winter months they were traditionally caught by lineboats on their home grounds. However, since

April 2008, lineboats may only catch snoek. This was done because their catches of kob over the

last six season has declined dramatically as they could not find the large kob on the traditional

fishing grounds. With this management measure in place we hope that the stock will recover

sufficiently.

Meanwhile the eggs will hatch and the larvae now drifts north with the current to the nursery and

juvenile grounds around Swakopmund in the WCRA. At this stage they might become the prey of

jellyfish and other small predators. Those that survive will grow rapidly and reach 30 cm within

one year and they will be hunted by larger fish such as snoek, sharks, skates and seabirds.

When these juveniles reach the age of approximately 2 years at about 40 cm, they will gradually

move north towards the adult home ground, the Skeleton Coast Park waters. This is also the size

at which about 50% of the population reaches sexual maturity. Therefore,to give them all a 50%

chance to reproduce at least once in their lifetime a minimum length of 40 cm was introduced in

2001.

Here in the relative safety of the Skeleton Coast Park they will feed and grow until they become

adults at the age of about 7 years. Now their growth will slow down to save that energy for

reproduction and to take part in the yearly spawning migration. So the life of a kob starts, comes

full cycle, and ends.