Question: why is Lesser-Spotted Catshark an option considering there is many species of sharks in the sea?

Lesser-Spotted Catshark answered on 22 Nov 2017:

If it were up to me and me alone we would sequence all of the sharks in the sea! Perhaps one day we will get there. But for now, we need to choose very carefully which species to sequence in order to maximise their use to science. The catshark is an extremely easy shark to work with both in the laboratory and in the field. This is why we call it a ‘model species’. By using a model species like the catshark we can learn about shark biology without the logistical problems associated with trying to study Great Whites or Whale Sharks in the laboratory. It may not be the biggest, the fastest, or the most endangered but it still has all of that fundamentally awesome shark biology packed in there: tooth conveyor belt, electroreception, cartilage skeleton etc.
Think of the catshark like an ‘ambassador of sharks’. It does a very good job of representing all sharks and will be an excellent start to the ultimate aim of sequencing even more shark genomes in the future!