The biggest issue with April is the wind. The seaweed will be dependent on the wind. Strong on-shore flow will push a lot of weed onto the beach. Offshore flow will hold it off.
Either way, there will be plenty of wind in April. There always is. High winds means rough surf which makes fishing the surf difficult to impossible. The seaweed only adds to the problems.
If you can overcome the winds, rough surf and seaweed you might have a shot at catching a shark.
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Mike
Buda/Port Aransas, TX