A person who processes hybrids must be permitted by the department and shall maintain invoices on permitted fish which are bought, sold, transferred, processed, or possessed in his facility. The invoice must show the date, species, and poundage of all transactions. The invoice must show the origin and destination of the product including permit numbers. If the processor fillets or mutilates the product, the product must be labeled as prescribed in this chapter before leaving the processing facility. Invoices must be maintained for three years. The permitted facility shall allow inspection and sampling by the department during business hours or when employees are present.