Sunshineinabag
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I heard Marlboro is dropping cigs and going cannabis!
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Say goodbye to Jaws!
Say goodbye to Jaws!
Sevengill sharks have moved in to fill the gap left by the disappearance of great whites from South African waters
An 18-year-study revealed unexpected consequences for ocean ecosystems
It follows the decline of great whites in False Bay, near Cape Town in South Africa
The recent disappearance has led to the emergence of another apex predator
Sevengill sharks closely resemble ancient relatives from the Jurassic period
They are unique for having seven gills instead of the typical five in most sharks
The decline in numbers of great white sharks in South Africa has led to the emergence of sevengill sharks, another predator from a different habitat.
New research which focused on sharks in the waters surrounding False Bay reveals the unexpected consequences following diminishing numbers of apex predators.
The study was conducted over eighteen years and documents the fall in numbers of great whites in the waters surrounding Seal Island since 2015.
The island, near Cape Town is famous for great white sharks breaching out the water in pursuit of seals.
However, since 2017 sightings of the famous predator featured in Jaws has sharply declined with sightings reported sometimes months apart.
Around this time sevengill began to show up for the first time and have been increasing in number ever since, the research said.
In the eighteen years, the researchers said that they had never seen sevengill sharks but they now dominate the area.
They suggest that the appearance of sevengill sharks at Seal Island was due to the disappearance of great whites.
This allows sevengills to exploit the area without risk of predation from great white sharks or competition with them for shared prey.
Sevengill sharks closely resemble relatives from the Jurassic period, unique for having seven gills instead of the typical five in most other sharks.
The findings are part of a long-term study since the year 2000 between shark researcher Neil Hammerschlag, of the University of Miami Rosenstiel School of Marine and Atmospheric Science, and wildlife naturalist Chris Fallows, of Apex Shark Expeditions.
Locations of Seal Island, a Cape fur seal rookery, (A) off the Western Cape of South Africa, within (B) False Bay. Historically, white sharks actively patrolled the waters of (C) Seal Island in the colder months. The only well-known aggregation site for sevengill sharks in False Bay is the inshore kelp beds of Millers Point (C), which is ~18 km southwest of Seal Island
They closely observed great whites from boats over 8,000 hours, during which time they recorded 6,333 shark sightings, and 8,076 attacks on seals.
The data revealed that in the number of great whites was stable until 2015 when they began to see a drop.
'In 2017 and 2018, their numbers reached an all-time low, with great whites completely disappearing from our surveys for weeks and months at a time,' said study lead author Dr Neil Hammerschlag.
'While the reasons for their decline and disappearance remains unknown, it provided a truly unique opportunity for us to see what happens to an ocean ecosystem following the loss of an apex predator.'
The study notes that it is probable that sevengill sharks may have 'visited' Seal Island prior to the decline in white sharks, but never were bold enough to approach our surface baits.
'While the reasons for their decline and disappearance remains unknown, it provided a truly unique opportunity for us to see what happens to an ocean ecosystem following the loss of an apex predator.'
The study does suggest possibilities for the decline in number of great whites since 2015 could be down to over-fishing or habitat loss hypothesised by mark-recapture, photo-ID and genetic analysis.
It is also possible that False Bay's white sharks have shifted their distributional range elsewhere due to shifts in environmental conditions or prey.
Previous research said that both species of sharks in the area are being preyed upon by killer whales.
This followed the discovery of several dead sevengill sharks of which the cause of death was originally a mystery.
It was only after experts examined the carcasses that they saw impressions from the gaping wounds were consistent with the 'flat-toothed' killer whale.
'Between 2015 and 2017, killer whales were sighted at a number of different locations along the west and south coasts of South Africa, including areas such as Struisbaai and Gansbaai,' the previous study wrote.
Their presence at these two sites was followed by the discovery of multiple shark carcasses between February and June 2017.
The findings were published in the online journal Scientific Reports.
Source: https://www.dailymail.co.uk/sciencetech/article-6699395/Food-chains-undergo-massive-changes-predators-lost.html
RMS
Say goodbye to Jaws!
Sevengill sharks have moved in to fill the gap left by the disappearance of great whites from South African waters
An 18-year-study revealed unexpected consequences for ocean ecosystems
It follows the decline of great whites in False Bay, near Cape Town in South Africa
The recent disappearance has led to the emergence of another apex predator
Sevengill sharks closely resemble ancient relatives from the Jurassic period
They are unique for having seven gills instead of the typical five in most sharks
The decline in numbers of great white sharks in South Africa has led to the emergence of sevengill sharks, another predator from a different habitat.
New research which focused on sharks in the waters surrounding False Bay reveals the unexpected consequences following diminishing numbers of apex predators.
The study was conducted over eighteen years and documents the fall in numbers of great whites in the waters surrounding Seal Island since 2015.
The island, near Cape Town is famous for great white sharks breaching out the water in pursuit of seals.
However, since 2017 sightings of the famous predator featured in Jaws has sharply declined with sightings reported sometimes months apart.
Around this time sevengill began to show up for the first time and have been increasing in number ever since, the research said.
In the eighteen years, the researchers said that they had never seen sevengill sharks but they now dominate the area.
They suggest that the appearance of sevengill sharks at Seal Island was due to the disappearance of great whites.
This allows sevengills to exploit the area without risk of predation from great white sharks or competition with them for shared prey.
Sevengill sharks closely resemble relatives from the Jurassic period, unique for having seven gills instead of the typical five in most other sharks.
The findings are part of a long-term study since the year 2000 between shark researcher Neil Hammerschlag, of the University of Miami Rosenstiel School of Marine and Atmospheric Science, and wildlife naturalist Chris Fallows, of Apex Shark Expeditions.
Locations of Seal Island, a Cape fur seal rookery, (A) off the Western Cape of South Africa, within (B) False Bay. Historically, white sharks actively patrolled the waters of (C) Seal Island in the colder months. The only well-known aggregation site for sevengill sharks in False Bay is the inshore kelp beds of Millers Point (C), which is ~18 km southwest of Seal Island
They closely observed great whites from boats over 8,000 hours, during which time they recorded 6,333 shark sightings, and 8,076 attacks on seals.
The data revealed that in the number of great whites was stable until 2015 when they began to see a drop.
'In 2017 and 2018, their numbers reached an all-time low, with great whites completely disappearing from our surveys for weeks and months at a time,' said study lead author Dr Neil Hammerschlag.
'While the reasons for their decline and disappearance remains unknown, it provided a truly unique opportunity for us to see what happens to an ocean ecosystem following the loss of an apex predator.'
The study notes that it is probable that sevengill sharks may have 'visited' Seal Island prior to the decline in white sharks, but never were bold enough to approach our surface baits.
'While the reasons for their decline and disappearance remains unknown, it provided a truly unique opportunity for us to see what happens to an ocean ecosystem following the loss of an apex predator.'
The study does suggest possibilities for the decline in number of great whites since 2015 could be down to over-fishing or habitat loss hypothesised by mark-recapture, photo-ID and genetic analysis.
It is also possible that False Bay's white sharks have shifted their distributional range elsewhere due to shifts in environmental conditions or prey.
Previous research said that both species of sharks in the area are being preyed upon by killer whales.
This followed the discovery of several dead sevengill sharks of which the cause of death was originally a mystery.
It was only after experts examined the carcasses that they saw impressions from the gaping wounds were consistent with the 'flat-toothed' killer whale.
'Between 2015 and 2017, killer whales were sighted at a number of different locations along the west and south coasts of South Africa, including areas such as Struisbaai and Gansbaai,' the previous study wrote.
Their presence at these two sites was followed by the discovery of multiple shark carcasses between February and June 2017.
The findings were published in the online journal Scientific Reports.
Source: https://www.dailymail.co.uk/sciencetech/article-6699395/Food-chains-undergo-massive-changes-predators-lost.html
RMS
R
Robrites
S
Sertaiz
that definitely qualifies for this thread, wow.
i'm sterile now too, but i'd be willing to give it a try. i won't even charge him either...
R
Robrites
R
Robrites
R
Robrites
R
Robrites
Now that's a cool story
R
Robrites
OK, you can stop now, we know who's on top 
